From: Daniel Vetter daniel.vetter@ffwll.ch

DRM is a lot more than a direct rendering manager nowadays, and there's also a bunch of things worth documenting for gpu driver developers outside of drivers/gpu/drm, like vgaarb, vga_switcheroo or the various hardware buses like host1x and ipu-v3.

To avoid further confusion let's rename the top-level to reflect reality.

And yes I'm already looking forward to when we need to replace the G in GPU with a * ;-)

Inspired by a thread with Lukas since he refused to include the vga_switcheroo docs into the drm docs because it's not drm.

Cc: Lukas Wunner lukas@wunner.de Signed-off-by: Daniel Vetter daniel.vetter@intel.com [Lukas: Drop BUG() easter egg in i915_gem_execbuffer.c spotted by Jani and fix typos in commit message.] Signed-off-by: Lukas Wunner lukas@wunner.de --- Documentation/DocBook/Makefile | 4 +- Documentation/DocBook/drm.tmpl | 4189 ---------------------------------------- Documentation/DocBook/gpu.tmpl | 4189 ++++++++++++++++++++++++++++++++++++++++ 3 files changed, 4191 insertions(+), 4191 deletions(-) delete mode 100644 Documentation/DocBook/drm.tmpl create mode 100644 Documentation/DocBook/gpu.tmpl

diff --git a/Documentation/DocBook/Makefile b/Documentation/DocBook/Makefile index 75b7d9b..2088200 100644 --- a/Documentation/DocBook/Makefile +++ b/Documentation/DocBook/Makefile @@ -14,10 +14,10 @@ DOCBOOKS := z8530book.xml device-drivers.xml \ genericirq.xml s390-drivers.xml uio-howto.xml scsi.xml \ 80211.xml debugobjects.xml sh.xml regulator.xml \ alsa-driver-api.xml writing-an-alsa-driver.xml \ - tracepoint.xml drm.xml media_api.xml w1.xml \ + tracepoint.xml gpu.xml media_api.xml w1.xml \ writing_musb_glue_layer.xml crypto-API.xml iio.xml

-MARKDOWNREADY := drm.xml +MARKDOWNREADY := gpu.xml

include Documentation/DocBook/media/Makefile

diff --git a/Documentation/DocBook/drm.tmpl b/Documentation/DocBook/drm.tmpl deleted file mode 100644 index da1060c..0000000 --- a/Documentation/DocBook/drm.tmpl +++ /dev/null @@ -1,4189 +0,0 @@ -<?xml version="1.0" encoding="UTF-8"?> -<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" - "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []> - -<book id="drmDevelopersGuide"> - <bookinfo> - <title>Linux DRM Developer's Guide</title> - - <authorgroup> - <author> - <firstname>Jesse</firstname> - <surname>Barnes</surname> - <contrib>Initial version</contrib> - <affiliation> - <orgname>Intel Corporation</orgname> - <address> - <email>jesse.barnes@intel.com</email> - </address> - </affiliation> - </author> - <author> - <firstname>Laurent</firstname> - <surname>Pinchart</surname> - <contrib>Driver internals</contrib> - <affiliation> - <orgname>Ideas on board SPRL</orgname> - <address> - <email>laurent.pinchart@ideasonboard.com</email> - </address> - </affiliation> - </author> - <author> - <firstname>Daniel</firstname> - <surname>Vetter</surname> - <contrib>Contributions all over the place</contrib> - <affiliation> - <orgname>Intel Corporation</orgname> - <address> - <email>daniel.vetter@ffwll.ch</email> - </address> - </affiliation> - </author> - </authorgroup> - - <copyright> - <year>2008-2009</year> - <year>2013-2014</year> - <holder>Intel Corporation</holder> - </copyright> - <copyright> - <year>2012</year> - <holder>Laurent Pinchart</holder> - </copyright> - - <legalnotice> - <para> - The contents of this file may be used under the terms of the GNU - General Public License version 2 (the "GPL") as distributed in - the kernel source COPYING file. - </para> - </legalnotice> - - <revhistory> - <!-- Put document revisions here, newest first. --> - <revision> - <revnumber>1.0</revnumber> - <date>2012-07-13</date> - <authorinitials>LP</authorinitials> - <revremark>Added extensive documentation about driver internals. - </revremark> - </revision> - </revhistory> - </bookinfo> - -<toc></toc> - -<part id="drmCore"> - <title>DRM Core</title> - <partintro> - <para> - This first part of the DRM Developer's Guide documents core DRM code, - helper libraries for writing drivers and generic userspace interfaces - exposed by DRM drivers. - </para> - </partintro> - - <chapter id="drmIntroduction"> - <title>Introduction</title> - <para> - The Linux DRM layer contains code intended to support the needs - of complex graphics devices, usually containing programmable - pipelines well suited to 3D graphics acceleration. Graphics - drivers in the kernel may make use of DRM functions to make - tasks like memory management, interrupt handling and DMA easier, - and provide a uniform interface to applications. - </para> - <para> - A note on versions: this guide covers features found in the DRM - tree, including the TTM memory manager, output configuration and - mode setting, and the new vblank internals, in addition to all - the regular features found in current kernels. - </para> - <para> - [Insert diagram of typical DRM stack here] - </para> - </chapter> - - <!-- Internals --> - - <chapter id="drmInternals"> - <title>DRM Internals</title> - <para> - This chapter documents DRM internals relevant to driver authors - and developers working to add support for the latest features to - existing drivers. - </para> - <para> - First, we go over some typical driver initialization - requirements, like setting up command buffers, creating an - initial output configuration, and initializing core services. - Subsequent sections cover core internals in more detail, - providing implementation notes and examples. - </para> - <para> - The DRM layer provides several services to graphics drivers, - many of them driven by the application interfaces it provides - through libdrm, the library that wraps most of the DRM ioctls. - These include vblank event handling, memory - management, output management, framebuffer management, command - submission &amp; fencing, suspend/resume support, and DMA - services. - </para> - - <!-- Internals: driver init --> - - <sect1> - <title>Driver Initialization</title> - <para> - At the core of every DRM driver is a <structname>drm_driver</structname> - structure. Drivers typically statically initialize a drm_driver structure, - and then pass it to one of the <function>drm_*_init()</function> functions - to register it with the DRM subsystem. - </para> - <para> - Newer drivers that no longer require a <structname>drm_bus</structname> - structure can alternatively use the low-level device initialization and - registration functions such as <function>drm_dev_alloc()</function> and - <function>drm_dev_register()</function> directly. - </para> - <para> - The <structname>drm_driver</structname> structure contains static - information that describes the driver and features it supports, and - pointers to methods that the DRM core will call to implement the DRM API. - We will first go through the <structname>drm_driver</structname> static - information fields, and will then describe individual operations in - details as they get used in later sections. - </para> - <sect2> - <title>Driver Information</title> - <sect3> - <title>Driver Features</title> - <para> - Drivers inform the DRM core about their requirements and supported - features by setting appropriate flags in the - <structfield>driver_features</structfield> field. Since those flags - influence the DRM core behaviour since registration time, most of them - must be set to registering the <structname>drm_driver</structname> - instance. - </para> - <synopsis>u32 driver_features;</synopsis> - <variablelist> - <title>Driver Feature Flags</title> - <varlistentry> - <term>DRIVER_USE_AGP</term> - <listitem><para> - Driver uses AGP interface, the DRM core will manage AGP resources. - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRIVER_REQUIRE_AGP</term> - <listitem><para> - Driver needs AGP interface to function. AGP initialization failure - will become a fatal error. - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRIVER_PCI_DMA</term> - <listitem><para> - Driver is capable of PCI DMA, mapping of PCI DMA buffers to - userspace will be enabled. Deprecated. - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRIVER_SG</term> - <listitem><para> - Driver can perform scatter/gather DMA, allocation and mapping of - scatter/gather buffers will be enabled. Deprecated. - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRIVER_HAVE_DMA</term> - <listitem><para> - Driver supports DMA, the userspace DMA API will be supported. - Deprecated. - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRIVER_HAVE_IRQ</term><term>DRIVER_IRQ_SHARED</term> - <listitem><para> - DRIVER_HAVE_IRQ indicates whether the driver has an IRQ handler - managed by the DRM Core. The core will support simple IRQ handler - installation when the flag is set. The installation process is - described in <xref linkend="drm-irq-registration"/>.</para> - <para>DRIVER_IRQ_SHARED indicates whether the device &amp; handler - support shared IRQs (note that this is required of PCI drivers). - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRIVER_GEM</term> - <listitem><para> - Driver use the GEM memory manager. - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRIVER_MODESET</term> - <listitem><para> - Driver supports mode setting interfaces (KMS). - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRIVER_PRIME</term> - <listitem><para> - Driver implements DRM PRIME buffer sharing. - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRIVER_RENDER</term> - <listitem><para> - Driver supports dedicated render nodes. - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRIVER_ATOMIC</term> - <listitem><para> - Driver supports atomic properties. In this case the driver - must implement appropriate obj->atomic_get_property() vfuncs - for any modeset objects with driver specific properties. - </para></listitem> - </varlistentry> - </variablelist> - </sect3> - <sect3> - <title>Major, Minor and Patchlevel</title> - <synopsis>int major; -int minor; -int patchlevel;</synopsis> - <para> - The DRM core identifies driver versions by a major, minor and patch - level triplet. The information is printed to the kernel log at - initialization time and passed to userspace through the - DRM_IOCTL_VERSION ioctl. - </para> - <para> - The major and minor numbers are also used to verify the requested driver - API version passed to DRM_IOCTL_SET_VERSION. When the driver API changes - between minor versions, applications can call DRM_IOCTL_SET_VERSION to - select a specific version of the API. If the requested major isn't equal - to the driver major, or the requested minor is larger than the driver - minor, the DRM_IOCTL_SET_VERSION call will return an error. Otherwise - the driver's set_version() method will be called with the requested - version. - </para> - </sect3> - <sect3> - <title>Name, Description and Date</title> - <synopsis>char *name; -char *desc; -char *date;</synopsis> - <para> - The driver name is printed to the kernel log at initialization time, - used for IRQ registration and passed to userspace through - DRM_IOCTL_VERSION. - </para> - <para> - The driver description is a purely informative string passed to - userspace through the DRM_IOCTL_VERSION ioctl and otherwise unused by - the kernel. - </para> - <para> - The driver date, formatted as YYYYMMDD, is meant to identify the date of - the latest modification to the driver. However, as most drivers fail to - update it, its value is mostly useless. The DRM core prints it to the - kernel log at initialization time and passes it to userspace through the - DRM_IOCTL_VERSION ioctl. - </para> - </sect3> - </sect2> - <sect2> - <title>Device Registration</title> - <para> - A number of functions are provided to help with device registration. - The functions deal with PCI and platform devices, respectively. - </para> -!Edrivers/gpu/drm/drm_pci.c -!Edrivers/gpu/drm/drm_platform.c - <para> - New drivers that no longer rely on the services provided by the - <structname>drm_bus</structname> structure can call the low-level - device registration functions directly. The - <function>drm_dev_alloc()</function> function can be used to allocate - and initialize a new <structname>drm_device</structname> structure. - Drivers will typically want to perform some additional setup on this - structure, such as allocating driver-specific data and storing a - pointer to it in the DRM device's <structfield>dev_private</structfield> - field. Drivers should also set the device's unique name using the - <function>drm_dev_set_unique()</function> function. After it has been - set up a device can be registered with the DRM subsystem by calling - <function>drm_dev_register()</function>. This will cause the device to - be exposed to userspace and will call the driver's - <structfield>.load()</structfield> implementation. When a device is - removed, the DRM device can safely be unregistered and freed by calling - <function>drm_dev_unregister()</function> followed by a call to - <function>drm_dev_unref()</function>. - </para> -!Edrivers/gpu/drm/drm_drv.c - </sect2> - <sect2> - <title>Driver Load</title> - <para> - The <methodname>load</methodname> method is the driver and device - initialization entry point. The method is responsible for allocating and - initializing driver private data, performing resource allocation and - mapping (e.g. acquiring - clocks, mapping registers or allocating command buffers), initializing - the memory manager (<xref linkend="drm-memory-management"/>), installing - the IRQ handler (<xref linkend="drm-irq-registration"/>), setting up - vertical blanking handling (<xref linkend="drm-vertical-blank"/>), mode - setting (<xref linkend="drm-mode-setting"/>) and initial output - configuration (<xref linkend="drm-kms-init"/>). - </para> - <note><para> - If compatibility is a concern (e.g. with drivers converted over from - User Mode Setting to Kernel Mode Setting), care must be taken to prevent - device initialization and control that is incompatible with currently - active userspace drivers. For instance, if user level mode setting - drivers are in use, it would be problematic to perform output discovery - &amp; configuration at load time. Likewise, if user-level drivers - unaware of memory management are in use, memory management and command - buffer setup may need to be omitted. These requirements are - driver-specific, and care needs to be taken to keep both old and new - applications and libraries working. - </para></note> - <synopsis>int (*load) (struct drm_device *, unsigned long flags);</synopsis> - <para> - The method takes two arguments, a pointer to the newly created - <structname>drm_device</structname> and flags. The flags are used to - pass the <structfield>driver_data</structfield> field of the device id - corresponding to the device passed to <function>drm_*_init()</function>. - Only PCI devices currently use this, USB and platform DRM drivers have - their <methodname>load</methodname> method called with flags to 0. - </para> - <sect3> - <title>Driver Private Data</title> - <para> - The driver private hangs off the main - <structname>drm_device</structname> structure and can be used for - tracking various device-specific bits of information, like register - offsets, command buffer status, register state for suspend/resume, etc. - At load time, a driver may simply allocate one and set - <structname>drm_device</structname>.<structfield>dev_priv</structfield> - appropriately; it should be freed and - <structname>drm_device</structname>.<structfield>dev_priv</structfield> - set to NULL when the driver is unloaded. - </para> - </sect3> - <sect3 id="drm-irq-registration"> - <title>IRQ Registration</title> - <para> - The DRM core tries to facilitate IRQ handler registration and - unregistration by providing <function>drm_irq_install</function> and - <function>drm_irq_uninstall</function> functions. Those functions only - support a single interrupt per device, devices that use more than one - IRQs need to be handled manually. - </para> - <sect4> - <title>Managed IRQ Registration</title> - <para> - <function>drm_irq_install</function> starts by calling the - <methodname>irq_preinstall</methodname> driver operation. The operation - is optional and must make sure that the interrupt will not get fired by - clearing all pending interrupt flags or disabling the interrupt. - </para> - <para> - The passed-in IRQ will then be requested by a call to - <function>request_irq</function>. If the DRIVER_IRQ_SHARED driver - feature flag is set, a shared (IRQF_SHARED) IRQ handler will be - requested. - </para> - <para> - The IRQ handler function must be provided as the mandatory irq_handler - driver operation. It will get passed directly to - <function>request_irq</function> and thus has the same prototype as all - IRQ handlers. It will get called with a pointer to the DRM device as the - second argument. - </para> - <para> - Finally the function calls the optional - <methodname>irq_postinstall</methodname> driver operation. The operation - usually enables interrupts (excluding the vblank interrupt, which is - enabled separately), but drivers may choose to enable/disable interrupts - at a different time. - </para> - <para> - <function>drm_irq_uninstall</function> is similarly used to uninstall an - IRQ handler. It starts by waking up all processes waiting on a vblank - interrupt to make sure they don't hang, and then calls the optional - <methodname>irq_uninstall</methodname> driver operation. The operation - must disable all hardware interrupts. Finally the function frees the IRQ - by calling <function>free_irq</function>. - </para> - </sect4> - <sect4> - <title>Manual IRQ Registration</title> - <para> - Drivers that require multiple interrupt handlers can't use the managed - IRQ registration functions. In that case IRQs must be registered and - unregistered manually (usually with the <function>request_irq</function> - and <function>free_irq</function> functions, or their devm_* equivalent). - </para> - <para> - When manually registering IRQs, drivers must not set the DRIVER_HAVE_IRQ - driver feature flag, and must not provide the - <methodname>irq_handler</methodname> driver operation. They must set the - <structname>drm_device</structname> <structfield>irq_enabled</structfield> - field to 1 upon registration of the IRQs, and clear it to 0 after - unregistering the IRQs. - </para> - </sect4> - </sect3> - <sect3> - <title>Memory Manager Initialization</title> - <para> - Every DRM driver requires a memory manager which must be initialized at - load time. DRM currently contains two memory managers, the Translation - Table Manager (TTM) and the Graphics Execution Manager (GEM). - This document describes the use of the GEM memory manager only. See - <xref linkend="drm-memory-management"/> for details. - </para> - </sect3> - <sect3> - <title>Miscellaneous Device Configuration</title> - <para> - Another task that may be necessary for PCI devices during configuration - is mapping the video BIOS. On many devices, the VBIOS describes device - configuration, LCD panel timings (if any), and contains flags indicating - device state. Mapping the BIOS can be done using the pci_map_rom() call, - a convenience function that takes care of mapping the actual ROM, - whether it has been shadowed into memory (typically at address 0xc0000) - or exists on the PCI device in the ROM BAR. Note that after the ROM has - been mapped and any necessary information has been extracted, it should - be unmapped; on many devices, the ROM address decoder is shared with - other BARs, so leaving it mapped could cause undesired behaviour like - hangs or memory corruption. - <!--!Fdrivers/pci/rom.c pci_map_rom--> - </para> - </sect3> - </sect2> - </sect1> - - <!-- Internals: memory management --> - - <sect1 id="drm-memory-management"> - <title>Memory management</title> - <para> - Modern Linux systems require large amount of graphics memory to store - frame buffers, textures, vertices and other graphics-related data. Given - the very dynamic nature of many of that data, managing graphics memory - efficiently is thus crucial for the graphics stack and plays a central - role in the DRM infrastructure. - </para> - <para> - The DRM core includes two memory managers, namely Translation Table Maps - (TTM) and Graphics Execution Manager (GEM). TTM was the first DRM memory - manager to be developed and tried to be a one-size-fits-them all - solution. It provides a single userspace API to accommodate the need of - all hardware, supporting both Unified Memory Architecture (UMA) devices - and devices with dedicated video RAM (i.e. most discrete video cards). - This resulted in a large, complex piece of code that turned out to be - hard to use for driver development. - </para> - <para> - GEM started as an Intel-sponsored project in reaction to TTM's - complexity. Its design philosophy is completely different: instead of - providing a solution to every graphics memory-related problems, GEM - identified common code between drivers and created a support library to - share it. GEM has simpler initialization and execution requirements than - TTM, but has no video RAM management capabilities and is thus limited to - UMA devices. - </para> - <sect2> - <title>The Translation Table Manager (TTM)</title> - <para> - TTM design background and information belongs here. - </para> - <sect3> - <title>TTM initialization</title> - <warning><para>This section is outdated.</para></warning> - <para> - Drivers wishing to support TTM must fill out a drm_bo_driver - structure. The structure contains several fields with function - pointers for initializing the TTM, allocating and freeing memory, - waiting for command completion and fence synchronization, and memory - migration. See the radeon_ttm.c file for an example of usage. - </para> - <para> - The ttm_global_reference structure is made up of several fields: - </para> - <programlisting> - struct ttm_global_reference { - enum ttm_global_types global_type; - size_t size; - void *object; - int (*init) (struct ttm_global_reference *); - void (*release) (struct ttm_global_reference *); - }; - </programlisting> - <para> - There should be one global reference structure for your memory - manager as a whole, and there will be others for each object - created by the memory manager at runtime. Your global TTM should - have a type of TTM_GLOBAL_TTM_MEM. The size field for the global - object should be sizeof(struct ttm_mem_global), and the init and - release hooks should point at your driver-specific init and - release routines, which probably eventually call - ttm_mem_global_init and ttm_mem_global_release, respectively. - </para> - <para> - Once your global TTM accounting structure is set up and initialized - by calling ttm_global_item_ref() on it, - you need to create a buffer object TTM to - provide a pool for buffer object allocation by clients and the - kernel itself. The type of this object should be TTM_GLOBAL_TTM_BO, - and its size should be sizeof(struct ttm_bo_global). Again, - driver-specific init and release functions may be provided, - likely eventually calling ttm_bo_global_init() and - ttm_bo_global_release(), respectively. Also, like the previous - object, ttm_global_item_ref() is used to create an initial reference - count for the TTM, which will call your initialization function. - </para> - </sect3> - </sect2> - <sect2 id="drm-gem"> - <title>The Graphics Execution Manager (GEM)</title> - <para> - The GEM design approach has resulted in a memory manager that doesn't - provide full coverage of all (or even all common) use cases in its - userspace or kernel API. GEM exposes a set of standard memory-related - operations to userspace and a set of helper functions to drivers, and let - drivers implement hardware-specific operations with their own private API. - </para> - <para> - The GEM userspace API is described in the - <ulink url="http://lwn.net/Articles/283798/"><citetitle>GEM - the Graphics - Execution Manager</citetitle></ulink> article on LWN. While slightly - outdated, the document provides a good overview of the GEM API principles. - Buffer allocation and read and write operations, described as part of the - common GEM API, are currently implemented using driver-specific ioctls. - </para> - <para> - GEM is data-agnostic. It manages abstract buffer objects without knowing - what individual buffers contain. APIs that require knowledge of buffer - contents or purpose, such as buffer allocation or synchronization - primitives, are thus outside of the scope of GEM and must be implemented - using driver-specific ioctls. - </para> - <para> - On a fundamental level, GEM involves several operations: - <itemizedlist> - <listitem>Memory allocation and freeing</listitem> - <listitem>Command execution</listitem> - <listitem>Aperture management at command execution time</listitem> - </itemizedlist> - Buffer object allocation is relatively straightforward and largely - provided by Linux's shmem layer, which provides memory to back each - object. - </para> - <para> - Device-specific operations, such as command execution, pinning, buffer - read &amp; write, mapping, and domain ownership transfers are left to - driver-specific ioctls. - </para> - <sect3> - <title>GEM Initialization</title> - <para> - Drivers that use GEM must set the DRIVER_GEM bit in the struct - <structname>drm_driver</structname> - <structfield>driver_features</structfield> field. The DRM core will - then automatically initialize the GEM core before calling the - <methodname>load</methodname> operation. Behind the scene, this will - create a DRM Memory Manager object which provides an address space - pool for object allocation. - </para> - <para> - In a KMS configuration, drivers need to allocate and initialize a - command ring buffer following core GEM initialization if required by - the hardware. UMA devices usually have what is called a "stolen" - memory region, which provides space for the initial framebuffer and - large, contiguous memory regions required by the device. This space is - typically not managed by GEM, and must be initialized separately into - its own DRM MM object. - </para> - </sect3> - <sect3> - <title>GEM Objects Creation</title> - <para> - GEM splits creation of GEM objects and allocation of the memory that - backs them in two distinct operations. - </para> - <para> - GEM objects are represented by an instance of struct - <structname>drm_gem_object</structname>. Drivers usually need to extend - GEM objects with private information and thus create a driver-specific - GEM object structure type that embeds an instance of struct - <structname>drm_gem_object</structname>. - </para> - <para> - To create a GEM object, a driver allocates memory for an instance of its - specific GEM object type and initializes the embedded struct - <structname>drm_gem_object</structname> with a call to - <function>drm_gem_object_init</function>. The function takes a pointer to - the DRM device, a pointer to the GEM object and the buffer object size - in bytes. - </para> - <para> - GEM uses shmem to allocate anonymous pageable memory. - <function>drm_gem_object_init</function> will create an shmfs file of - the requested size and store it into the struct - <structname>drm_gem_object</structname> <structfield>filp</structfield> - field. The memory is used as either main storage for the object when the - graphics hardware uses system memory directly or as a backing store - otherwise. - </para> - <para> - Drivers are responsible for the actual physical pages allocation by - calling <function>shmem_read_mapping_page_gfp</function> for each page. - Note that they can decide to allocate pages when initializing the GEM - object, or to delay allocation until the memory is needed (for instance - when a page fault occurs as a result of a userspace memory access or - when the driver needs to start a DMA transfer involving the memory). - </para> - <para> - Anonymous pageable memory allocation is not always desired, for instance - when the hardware requires physically contiguous system memory as is - often the case in embedded devices. Drivers can create GEM objects with - no shmfs backing (called private GEM objects) by initializing them with - a call to <function>drm_gem_private_object_init</function> instead of - <function>drm_gem_object_init</function>. Storage for private GEM - objects must be managed by drivers. - </para> - <para> - Drivers that do not need to extend GEM objects with private information - can call the <function>drm_gem_object_alloc</function> function to - allocate and initialize a struct <structname>drm_gem_object</structname> - instance. The GEM core will call the optional driver - <methodname>gem_init_object</methodname> operation after initializing - the GEM object with <function>drm_gem_object_init</function>. - <synopsis>int (*gem_init_object) (struct drm_gem_object *obj);</synopsis> - </para> - <para> - No alloc-and-init function exists for private GEM objects. - </para> - </sect3> - <sect3> - <title>GEM Objects Lifetime</title> - <para> - All GEM objects are reference-counted by the GEM core. References can be - acquired and release by <function>calling drm_gem_object_reference</function> - and <function>drm_gem_object_unreference</function> respectively. The - caller must hold the <structname>drm_device</structname> - <structfield>struct_mutex</structfield> lock. As a convenience, GEM - provides the <function>drm_gem_object_reference_unlocked</function> and - <function>drm_gem_object_unreference_unlocked</function> functions that - can be called without holding the lock. - </para> - <para> - When the last reference to a GEM object is released the GEM core calls - the <structname>drm_driver</structname> - <methodname>gem_free_object</methodname> operation. That operation is - mandatory for GEM-enabled drivers and must free the GEM object and all - associated resources. - </para> - <para> - <synopsis>void (*gem_free_object) (struct drm_gem_object *obj);</synopsis> - Drivers are responsible for freeing all GEM object resources, including - the resources created by the GEM core. If an mmap offset has been - created for the object (in which case - <structname>drm_gem_object</structname>::<structfield>map_list</structfield>::<structfield>map</structfield> - is not NULL) it must be freed by a call to - <function>drm_gem_free_mmap_offset</function>. The shmfs backing store - must be released by calling <function>drm_gem_object_release</function> - (that function can safely be called if no shmfs backing store has been - created). - </para> - </sect3> - <sect3> - <title>GEM Objects Naming</title> - <para> - Communication between userspace and the kernel refers to GEM objects - using local handles, global names or, more recently, file descriptors. - All of those are 32-bit integer values; the usual Linux kernel limits - apply to the file descriptors. - </para> - <para> - GEM handles are local to a DRM file. Applications get a handle to a GEM - object through a driver-specific ioctl, and can use that handle to refer - to the GEM object in other standard or driver-specific ioctls. Closing a - DRM file handle frees all its GEM handles and dereferences the - associated GEM objects. - </para> - <para> - To create a handle for a GEM object drivers call - <function>drm_gem_handle_create</function>. The function takes a pointer - to the DRM file and the GEM object and returns a locally unique handle. - When the handle is no longer needed drivers delete it with a call to - <function>drm_gem_handle_delete</function>. Finally the GEM object - associated with a handle can be retrieved by a call to - <function>drm_gem_object_lookup</function>. - </para> - <para> - Handles don't take ownership of GEM objects, they only take a reference - to the object that will be dropped when the handle is destroyed. To - avoid leaking GEM objects, drivers must make sure they drop the - reference(s) they own (such as the initial reference taken at object - creation time) as appropriate, without any special consideration for the - handle. For example, in the particular case of combined GEM object and - handle creation in the implementation of the - <methodname>dumb_create</methodname> operation, drivers must drop the - initial reference to the GEM object before returning the handle. - </para> - <para> - GEM names are similar in purpose to handles but are not local to DRM - files. They can be passed between processes to reference a GEM object - globally. Names can't be used directly to refer to objects in the DRM - API, applications must convert handles to names and names to handles - using the DRM_IOCTL_GEM_FLINK and DRM_IOCTL_GEM_OPEN ioctls - respectively. The conversion is handled by the DRM core without any - driver-specific support. - </para> - <para> - GEM also supports buffer sharing with dma-buf file descriptors through - PRIME. GEM-based drivers must use the provided helpers functions to - implement the exporting and importing correctly. See <xref linkend="drm-prime-support" />. - Since sharing file descriptors is inherently more secure than the - easily guessable and global GEM names it is the preferred buffer - sharing mechanism. Sharing buffers through GEM names is only supported - for legacy userspace. Furthermore PRIME also allows cross-device - buffer sharing since it is based on dma-bufs. - </para> - </sect3> - <sect3 id="drm-gem-objects-mapping"> - <title>GEM Objects Mapping</title> - <para> - Because mapping operations are fairly heavyweight GEM favours - read/write-like access to buffers, implemented through driver-specific - ioctls, over mapping buffers to userspace. However, when random access - to the buffer is needed (to perform software rendering for instance), - direct access to the object can be more efficient. - </para> - <para> - The mmap system call can't be used directly to map GEM objects, as they - don't have their own file handle. Two alternative methods currently - co-exist to map GEM objects to userspace. The first method uses a - driver-specific ioctl to perform the mapping operation, calling - <function>do_mmap</function> under the hood. This is often considered - dubious, seems to be discouraged for new GEM-enabled drivers, and will - thus not be described here. - </para> - <para> - The second method uses the mmap system call on the DRM file handle. - <synopsis>void *mmap(void *addr, size_t length, int prot, int flags, int fd, - off_t offset);</synopsis> - DRM identifies the GEM object to be mapped by a fake offset passed - through the mmap offset argument. Prior to being mapped, a GEM object - must thus be associated with a fake offset. To do so, drivers must call - <function>drm_gem_create_mmap_offset</function> on the object. The - function allocates a fake offset range from a pool and stores the - offset divided by PAGE_SIZE in - <literal>obj-&gt;map_list.hash.key</literal>. Care must be taken not to - call <function>drm_gem_create_mmap_offset</function> if a fake offset - has already been allocated for the object. This can be tested by - <literal>obj-&gt;map_list.map</literal> being non-NULL. - </para> - <para> - Once allocated, the fake offset value - (<literal>obj-&gt;map_list.hash.key &lt;&lt; PAGE_SHIFT</literal>) - must be passed to the application in a driver-specific way and can then - be used as the mmap offset argument. - </para> - <para> - The GEM core provides a helper method <function>drm_gem_mmap</function> - to handle object mapping. The method can be set directly as the mmap - file operation handler. It will look up the GEM object based on the - offset value and set the VMA operations to the - <structname>drm_driver</structname> <structfield>gem_vm_ops</structfield> - field. Note that <function>drm_gem_mmap</function> doesn't map memory to - userspace, but relies on the driver-provided fault handler to map pages - individually. - </para> - <para> - To use <function>drm_gem_mmap</function>, drivers must fill the struct - <structname>drm_driver</structname> <structfield>gem_vm_ops</structfield> - field with a pointer to VM operations. - </para> - <para> - <synopsis>struct vm_operations_struct *gem_vm_ops - - struct vm_operations_struct { - void (*open)(struct vm_area_struct * area); - void (*close)(struct vm_area_struct * area); - int (*fault)(struct vm_area_struct *vma, struct vm_fault *vmf); - };</synopsis> - </para> - <para> - The <methodname>open</methodname> and <methodname>close</methodname> - operations must update the GEM object reference count. Drivers can use - the <function>drm_gem_vm_open</function> and - <function>drm_gem_vm_close</function> helper functions directly as open - and close handlers. - </para> - <para> - The fault operation handler is responsible for mapping individual pages - to userspace when a page fault occurs. Depending on the memory - allocation scheme, drivers can allocate pages at fault time, or can - decide to allocate memory for the GEM object at the time the object is - created. - </para> - <para> - Drivers that want to map the GEM object upfront instead of handling page - faults can implement their own mmap file operation handler. - </para> - </sect3> - <sect3> - <title>Memory Coherency</title> - <para> - When mapped to the device or used in a command buffer, backing pages - for an object are flushed to memory and marked write combined so as to - be coherent with the GPU. Likewise, if the CPU accesses an object - after the GPU has finished rendering to the object, then the object - must be made coherent with the CPU's view of memory, usually involving - GPU cache flushing of various kinds. This core CPU&lt;-&gt;GPU - coherency management is provided by a device-specific ioctl, which - evaluates an object's current domain and performs any necessary - flushing or synchronization to put the object into the desired - coherency domain (note that the object may be busy, i.e. an active - render target; in that case, setting the domain blocks the client and - waits for rendering to complete before performing any necessary - flushing operations). - </para> - </sect3> - <sect3> - <title>Command Execution</title> - <para> - Perhaps the most important GEM function for GPU devices is providing a - command execution interface to clients. Client programs construct - command buffers containing references to previously allocated memory - objects, and then submit them to GEM. At that point, GEM takes care to - bind all the objects into the GTT, execute the buffer, and provide - necessary synchronization between clients accessing the same buffers. - This often involves evicting some objects from the GTT and re-binding - others (a fairly expensive operation), and providing relocation - support which hides fixed GTT offsets from clients. Clients must take - care not to submit command buffers that reference more objects than - can fit in the GTT; otherwise, GEM will reject them and no rendering - will occur. Similarly, if several objects in the buffer require fence - registers to be allocated for correct rendering (e.g. 2D blits on - pre-965 chips), care must be taken not to require more fence registers - than are available to the client. Such resource management should be - abstracted from the client in libdrm. - </para> - </sect3> - <sect3> - <title>GEM Function Reference</title> -!Edrivers/gpu/drm/drm_gem.c - </sect3> - </sect2> - <sect2> - <title>VMA Offset Manager</title> -!Pdrivers/gpu/drm/drm_vma_manager.c vma offset manager -!Edrivers/gpu/drm/drm_vma_manager.c -!Iinclude/drm/drm_vma_manager.h - </sect2> - <sect2 id="drm-prime-support"> - <title>PRIME Buffer Sharing</title> - <para> - PRIME is the cross device buffer sharing framework in drm, originally - created for the OPTIMUS range of multi-gpu platforms. To userspace - PRIME buffers are dma-buf based file descriptors. - </para> - <sect3> - <title>Overview and Driver Interface</title> - <para> - Similar to GEM global names, PRIME file descriptors are - also used to share buffer objects across processes. They offer - additional security: as file descriptors must be explicitly sent over - UNIX domain sockets to be shared between applications, they can't be - guessed like the globally unique GEM names. - </para> - <para> - Drivers that support the PRIME - API must set the DRIVER_PRIME bit in the struct - <structname>drm_driver</structname> - <structfield>driver_features</structfield> field, and implement the - <methodname>prime_handle_to_fd</methodname> and - <methodname>prime_fd_to_handle</methodname> operations. - </para> - <para> - <synopsis>int (*prime_handle_to_fd)(struct drm_device *dev, - struct drm_file *file_priv, uint32_t handle, - uint32_t flags, int *prime_fd); -int (*prime_fd_to_handle)(struct drm_device *dev, - struct drm_file *file_priv, int prime_fd, - uint32_t *handle);</synopsis> - Those two operations convert a handle to a PRIME file descriptor and - vice versa. Drivers must use the kernel dma-buf buffer sharing framework - to manage the PRIME file descriptors. Similar to the mode setting - API PRIME is agnostic to the underlying buffer object manager, as - long as handles are 32bit unsigned integers. - </para> - <para> - While non-GEM drivers must implement the operations themselves, GEM - drivers must use the <function>drm_gem_prime_handle_to_fd</function> - and <function>drm_gem_prime_fd_to_handle</function> helper functions. - Those helpers rely on the driver - <methodname>gem_prime_export</methodname> and - <methodname>gem_prime_import</methodname> operations to create a dma-buf - instance from a GEM object (dma-buf exporter role) and to create a GEM - object from a dma-buf instance (dma-buf importer role). - </para> - <para> - <synopsis>struct dma_buf * (*gem_prime_export)(struct drm_device *dev, - struct drm_gem_object *obj, - int flags); -struct drm_gem_object * (*gem_prime_import)(struct drm_device *dev, - struct dma_buf *dma_buf);</synopsis> - These two operations are mandatory for GEM drivers that support - PRIME. - </para> - </sect3> - <sect3> - <title>PRIME Helper Functions</title> -!Pdrivers/gpu/drm/drm_prime.c PRIME Helpers - </sect3> - </sect2> - <sect2> - <title>PRIME Function References</title> -!Edrivers/gpu/drm/drm_prime.c - </sect2> - <sect2> - <title>DRM MM Range Allocator</title> - <sect3> - <title>Overview</title> -!Pdrivers/gpu/drm/drm_mm.c Overview - </sect3> - <sect3> - <title>LRU Scan/Eviction Support</title> -!Pdrivers/gpu/drm/drm_mm.c lru scan roaster - </sect3> - </sect2> - <sect2> - <title>DRM MM Range Allocator Function References</title> -!Edrivers/gpu/drm/drm_mm.c -!Iinclude/drm/drm_mm.h - </sect2> - <sect2> - <title>CMA Helper Functions Reference</title> -!Pdrivers/gpu/drm/drm_gem_cma_helper.c cma helpers -!Edrivers/gpu/drm/drm_gem_cma_helper.c -!Iinclude/drm/drm_gem_cma_helper.h - </sect2> - </sect1> - - <!-- Internals: mode setting --> - - <sect1 id="drm-mode-setting"> - <title>Mode Setting</title> - <para> - Drivers must initialize the mode setting core by calling - <function>drm_mode_config_init</function> on the DRM device. The function - initializes the <structname>drm_device</structname> - <structfield>mode_config</structfield> field and never fails. Once done, - mode configuration must be setup by initializing the following fields. - </para> - <itemizedlist> - <listitem> - <synopsis>int min_width, min_height; -int max_width, max_height;</synopsis> - <para> - Minimum and maximum width and height of the frame buffers in pixel - units. - </para> - </listitem> - <listitem> - <synopsis>struct drm_mode_config_funcs *funcs;</synopsis> - <para>Mode setting functions.</para> - </listitem> - </itemizedlist> - <sect2> - <title>Display Modes Function Reference</title> -!Iinclude/drm/drm_modes.h -!Edrivers/gpu/drm/drm_modes.c - </sect2> - <sect2> - <title>Atomic Mode Setting Function Reference</title> -!Edrivers/gpu/drm/drm_atomic.c - </sect2> - <sect2> - <title>Frame Buffer Creation</title> - <synopsis>struct drm_framebuffer *(*fb_create)(struct drm_device *dev, - struct drm_file *file_priv, - struct drm_mode_fb_cmd2 *mode_cmd);</synopsis> - <para> - Frame buffers are abstract memory objects that provide a source of - pixels to scanout to a CRTC. Applications explicitly request the - creation of frame buffers through the DRM_IOCTL_MODE_ADDFB(2) ioctls and - receive an opaque handle that can be passed to the KMS CRTC control, - plane configuration and page flip functions. - </para> - <para> - Frame buffers rely on the underneath memory manager for low-level memory - operations. When creating a frame buffer applications pass a memory - handle (or a list of memory handles for multi-planar formats) through - the <parameter>drm_mode_fb_cmd2</parameter> argument. For drivers using - GEM as their userspace buffer management interface this would be a GEM - handle. Drivers are however free to use their own backing storage object - handles, e.g. vmwgfx directly exposes special TTM handles to userspace - and so expects TTM handles in the create ioctl and not GEM handles. - </para> - <para> - Drivers must first validate the requested frame buffer parameters passed - through the mode_cmd argument. In particular this is where invalid - sizes, pixel formats or pitches can be caught. - </para> - <para> - If the parameters are deemed valid, drivers then create, initialize and - return an instance of struct <structname>drm_framebuffer</structname>. - If desired the instance can be embedded in a larger driver-specific - structure. Drivers must fill its <structfield>width</structfield>, - <structfield>height</structfield>, <structfield>pitches</structfield>, - <structfield>offsets</structfield>, <structfield>depth</structfield>, - <structfield>bits_per_pixel</structfield> and - <structfield>pixel_format</structfield> fields from the values passed - through the <parameter>drm_mode_fb_cmd2</parameter> argument. They - should call the <function>drm_helper_mode_fill_fb_struct</function> - helper function to do so. - </para> - - <para> - The initialization of the new framebuffer instance is finalized with a - call to <function>drm_framebuffer_init</function> which takes a pointer - to DRM frame buffer operations (struct - <structname>drm_framebuffer_funcs</structname>). Note that this function - publishes the framebuffer and so from this point on it can be accessed - concurrently from other threads. Hence it must be the last step in the - driver's framebuffer initialization sequence. Frame buffer operations - are - <itemizedlist> - <listitem> - <synopsis>int (*create_handle)(struct drm_framebuffer *fb, - struct drm_file *file_priv, unsigned int *handle);</synopsis> - <para> - Create a handle to the frame buffer underlying memory object. If - the frame buffer uses a multi-plane format, the handle will - reference the memory object associated with the first plane. - </para> - <para> - Drivers call <function>drm_gem_handle_create</function> to create - the handle. - </para> - </listitem> - <listitem> - <synopsis>void (*destroy)(struct drm_framebuffer *framebuffer);</synopsis> - <para> - Destroy the frame buffer object and frees all associated - resources. Drivers must call - <function>drm_framebuffer_cleanup</function> to free resources - allocated by the DRM core for the frame buffer object, and must - make sure to unreference all memory objects associated with the - frame buffer. Handles created by the - <methodname>create_handle</methodname> operation are released by - the DRM core. - </para> - </listitem> - <listitem> - <synopsis>int (*dirty)(struct drm_framebuffer *framebuffer, - struct drm_file *file_priv, unsigned flags, unsigned color, - struct drm_clip_rect *clips, unsigned num_clips);</synopsis> - <para> - This optional operation notifies the driver that a region of the - frame buffer has changed in response to a DRM_IOCTL_MODE_DIRTYFB - ioctl call. - </para> - </listitem> - </itemizedlist> - </para> - <para> - The lifetime of a drm framebuffer is controlled with a reference count, - drivers can grab additional references with - <function>drm_framebuffer_reference</function>and drop them - again with <function>drm_framebuffer_unreference</function>. For - driver-private framebuffers for which the last reference is never - dropped (e.g. for the fbdev framebuffer when the struct - <structname>drm_framebuffer</structname> is embedded into the fbdev - helper struct) drivers can manually clean up a framebuffer at module - unload time with - <function>drm_framebuffer_unregister_private</function>. - </para> - </sect2> - <sect2> - <title>Dumb Buffer Objects</title> - <para> - The KMS API doesn't standardize backing storage object creation and - leaves it to driver-specific ioctls. Furthermore actually creating a - buffer object even for GEM-based drivers is done through a - driver-specific ioctl - GEM only has a common userspace interface for - sharing and destroying objects. While not an issue for full-fledged - graphics stacks that include device-specific userspace components (in - libdrm for instance), this limit makes DRM-based early boot graphics - unnecessarily complex. - </para> - <para> - Dumb objects partly alleviate the problem by providing a standard - API to create dumb buffers suitable for scanout, which can then be used - to create KMS frame buffers. - </para> - <para> - To support dumb objects drivers must implement the - <methodname>dumb_create</methodname>, - <methodname>dumb_destroy</methodname> and - <methodname>dumb_map_offset</methodname> operations. - </para> - <itemizedlist> - <listitem> - <synopsis>int (*dumb_create)(struct drm_file *file_priv, struct drm_device *dev, - struct drm_mode_create_dumb *args);</synopsis> - <para> - The <methodname>dumb_create</methodname> operation creates a driver - object (GEM or TTM handle) suitable for scanout based on the - width, height and depth from the struct - <structname>drm_mode_create_dumb</structname> argument. It fills the - argument's <structfield>handle</structfield>, - <structfield>pitch</structfield> and <structfield>size</structfield> - fields with a handle for the newly created object and its line - pitch and size in bytes. - </para> - </listitem> - <listitem> - <synopsis>int (*dumb_destroy)(struct drm_file *file_priv, struct drm_device *dev, - uint32_t handle);</synopsis> - <para> - The <methodname>dumb_destroy</methodname> operation destroys a dumb - object created by <methodname>dumb_create</methodname>. - </para> - </listitem> - <listitem> - <synopsis>int (*dumb_map_offset)(struct drm_file *file_priv, struct drm_device *dev, - uint32_t handle, uint64_t *offset);</synopsis> - <para> - The <methodname>dumb_map_offset</methodname> operation associates an - mmap fake offset with the object given by the handle and returns - it. Drivers must use the - <function>drm_gem_create_mmap_offset</function> function to - associate the fake offset as described in - <xref linkend="drm-gem-objects-mapping"/>. - </para> - </listitem> - </itemizedlist> - <para> - Note that dumb objects may not be used for gpu acceleration, as has been - attempted on some ARM embedded platforms. Such drivers really must have - a hardware-specific ioctl to allocate suitable buffer objects. - </para> - </sect2> - <sect2> - <title>Output Polling</title> - <synopsis>void (*output_poll_changed)(struct drm_device *dev);</synopsis> - <para> - This operation notifies the driver that the status of one or more - connectors has changed. Drivers that use the fb helper can just call the - <function>drm_fb_helper_hotplug_event</function> function to handle this - operation. - </para> - </sect2> - <sect2> - <title>Locking</title> - <para> - Beside some lookup structures with their own locking (which is hidden - behind the interface functions) most of the modeset state is protected - by the <code>dev-&lt;mode_config.lock</code> mutex and additionally - per-crtc locks to allow cursor updates, pageflips and similar operations - to occur concurrently with background tasks like output detection. - Operations which cross domains like a full modeset always grab all - locks. Drivers there need to protect resources shared between crtcs with - additional locking. They also need to be careful to always grab the - relevant crtc locks if a modset functions touches crtc state, e.g. for - load detection (which does only grab the <code>mode_config.lock</code> - to allow concurrent screen updates on live crtcs). - </para> - </sect2> - </sect1> - - <!-- Internals: kms initialization and cleanup --> - - <sect1 id="drm-kms-init"> - <title>KMS Initialization and Cleanup</title> - <para> - A KMS device is abstracted and exposed as a set of planes, CRTCs, encoders - and connectors. KMS drivers must thus create and initialize all those - objects at load time after initializing mode setting. - </para> - <sect2> - <title>CRTCs (struct <structname>drm_crtc</structname>)</title> - <para> - A CRTC is an abstraction representing a part of the chip that contains a - pointer to a scanout buffer. Therefore, the number of CRTCs available - determines how many independent scanout buffers can be active at any - given time. The CRTC structure contains several fields to support this: - a pointer to some video memory (abstracted as a frame buffer object), a - display mode, and an (x, y) offset into the video memory to support - panning or configurations where one piece of video memory spans multiple - CRTCs. - </para> - <sect3> - <title>CRTC Initialization</title> - <para> - A KMS device must create and register at least one struct - <structname>drm_crtc</structname> instance. The instance is allocated - and zeroed by the driver, possibly as part of a larger structure, and - registered with a call to <function>drm_crtc_init</function> with a - pointer to CRTC functions. - </para> - </sect3> - <sect3 id="drm-kms-crtcops"> - <title>CRTC Operations</title> - <sect4> - <title>Set Configuration</title> - <synopsis>int (*set_config)(struct drm_mode_set *set);</synopsis> - <para> - Apply a new CRTC configuration to the device. The configuration - specifies a CRTC, a frame buffer to scan out from, a (x,y) position in - the frame buffer, a display mode and an array of connectors to drive - with the CRTC if possible. - </para> - <para> - If the frame buffer specified in the configuration is NULL, the driver - must detach all encoders connected to the CRTC and all connectors - attached to those encoders and disable them. - </para> - <para> - This operation is called with the mode config lock held. - </para> - <note><para> - Note that the drm core has no notion of restoring the mode setting - state after resume, since all resume handling is in the full - responsibility of the driver. The common mode setting helper library - though provides a helper which can be used for this: - <function>drm_helper_resume_force_mode</function>. - </para></note> - </sect4> - <sect4> - <title>Page Flipping</title> - <synopsis>int (*page_flip)(struct drm_crtc *crtc, struct drm_framebuffer *fb, - struct drm_pending_vblank_event *event);</synopsis> - <para> - Schedule a page flip to the given frame buffer for the CRTC. This - operation is called with the mode config mutex held. - </para> - <para> - Page flipping is a synchronization mechanism that replaces the frame - buffer being scanned out by the CRTC with a new frame buffer during - vertical blanking, avoiding tearing. When an application requests a page - flip the DRM core verifies that the new frame buffer is large enough to - be scanned out by the CRTC in the currently configured mode and then - calls the CRTC <methodname>page_flip</methodname> operation with a - pointer to the new frame buffer. - </para> - <para> - The <methodname>page_flip</methodname> operation schedules a page flip. - Once any pending rendering targeting the new frame buffer has - completed, the CRTC will be reprogrammed to display that frame buffer - after the next vertical refresh. The operation must return immediately - without waiting for rendering or page flip to complete and must block - any new rendering to the frame buffer until the page flip completes. - </para> - <para> - If a page flip can be successfully scheduled the driver must set the - <code>drm_crtc-&gt;fb</code> field to the new framebuffer pointed to - by <code>fb</code>. This is important so that the reference counting - on framebuffers stays balanced. - </para> - <para> - If a page flip is already pending, the - <methodname>page_flip</methodname> operation must return - -<errorname>EBUSY</errorname>. - </para> - <para> - To synchronize page flip to vertical blanking the driver will likely - need to enable vertical blanking interrupts. It should call - <function>drm_vblank_get</function> for that purpose, and call - <function>drm_vblank_put</function> after the page flip completes. - </para> - <para> - If the application has requested to be notified when page flip completes - the <methodname>page_flip</methodname> operation will be called with a - non-NULL <parameter>event</parameter> argument pointing to a - <structname>drm_pending_vblank_event</structname> instance. Upon page - flip completion the driver must call <methodname>drm_send_vblank_event</methodname> - to fill in the event and send to wake up any waiting processes. - This can be performed with - <programlisting><![CDATA[ - spin_lock_irqsave(&dev->event_lock, flags); - ... - drm_send_vblank_event(dev, pipe, event); - spin_unlock_irqrestore(&dev->event_lock, flags); - ]]></programlisting> - </para> - <note><para> - FIXME: Could drivers that don't need to wait for rendering to complete - just add the event to <literal>dev-&gt;vblank_event_list</literal> and - let the DRM core handle everything, as for "normal" vertical blanking - events? - </para></note> - <para> - While waiting for the page flip to complete, the - <literal>event-&gt;base.link</literal> list head can be used freely by - the driver to store the pending event in a driver-specific list. - </para> - <para> - If the file handle is closed before the event is signaled, drivers must - take care to destroy the event in their - <methodname>preclose</methodname> operation (and, if needed, call - <function>drm_vblank_put</function>). - </para> - </sect4> - <sect4> - <title>Miscellaneous</title> - <itemizedlist> - <listitem> - <synopsis>void (*set_property)(struct drm_crtc *crtc, - struct drm_property *property, uint64_t value);</synopsis> - <para> - Set the value of the given CRTC property to - <parameter>value</parameter>. See <xref linkend="drm-kms-properties"/> - for more information about properties. - </para> - </listitem> - <listitem> - <synopsis>void (*gamma_set)(struct drm_crtc *crtc, u16 *r, u16 *g, u16 *b, - uint32_t start, uint32_t size);</synopsis> - <para> - Apply a gamma table to the device. The operation is optional. - </para> - </listitem> - <listitem> - <synopsis>void (*destroy)(struct drm_crtc *crtc);</synopsis> - <para> - Destroy the CRTC when not needed anymore. See - <xref linkend="drm-kms-init"/>. - </para> - </listitem> - </itemizedlist> - </sect4> - </sect3> - </sect2> - <sect2> - <title>Planes (struct <structname>drm_plane</structname>)</title> - <para> - A plane represents an image source that can be blended with or overlayed - on top of a CRTC during the scanout process. Planes are associated with - a frame buffer to crop a portion of the image memory (source) and - optionally scale it to a destination size. The result is then blended - with or overlayed on top of a CRTC. - </para> - <para> - The DRM core recognizes three types of planes: - <itemizedlist> - <listitem> - DRM_PLANE_TYPE_PRIMARY represents a "main" plane for a CRTC. Primary - planes are the planes operated upon by CRTC modesetting and flipping - operations described in <xref linkend="drm-kms-crtcops"/>. - </listitem> - <listitem> - DRM_PLANE_TYPE_CURSOR represents a "cursor" plane for a CRTC. Cursor - planes are the planes operated upon by the DRM_IOCTL_MODE_CURSOR and - DRM_IOCTL_MODE_CURSOR2 ioctls. - </listitem> - <listitem> - DRM_PLANE_TYPE_OVERLAY represents all non-primary, non-cursor planes. - Some drivers refer to these types of planes as "sprites" internally. - </listitem> - </itemizedlist> - For compatibility with legacy userspace, only overlay planes are made - available to userspace by default. Userspace clients may set the - DRM_CLIENT_CAP_UNIVERSAL_PLANES client capability bit to indicate that - they wish to receive a universal plane list containing all plane types. - </para> - <sect3> - <title>Plane Initialization</title> - <para> - To create a plane, a KMS drivers allocates and - zeroes an instances of struct <structname>drm_plane</structname> - (possibly as part of a larger structure) and registers it with a call - to <function>drm_universal_plane_init</function>. The function takes a bitmask - of the CRTCs that can be associated with the plane, a pointer to the - plane functions, a list of format supported formats, and the type of - plane (primary, cursor, or overlay) being initialized. - </para> - <para> - Cursor and overlay planes are optional. All drivers should provide - one primary plane per CRTC (although this requirement may change in - the future); drivers that do not wish to provide special handling for - primary planes may make use of the helper functions described in - <xref linkend="drm-kms-planehelpers"/> to create and register a - primary plane with standard capabilities. - </para> - </sect3> - <sect3> - <title>Plane Operations</title> - <itemizedlist> - <listitem> - <synopsis>int (*update_plane)(struct drm_plane *plane, struct drm_crtc *crtc, - struct drm_framebuffer *fb, int crtc_x, int crtc_y, - unsigned int crtc_w, unsigned int crtc_h, - uint32_t src_x, uint32_t src_y, - uint32_t src_w, uint32_t src_h);</synopsis> - <para> - Enable and configure the plane to use the given CRTC and frame buffer. - </para> - <para> - The source rectangle in frame buffer memory coordinates is given by - the <parameter>src_x</parameter>, <parameter>src_y</parameter>, - <parameter>src_w</parameter> and <parameter>src_h</parameter> - parameters (as 16.16 fixed point values). Devices that don't support - subpixel plane coordinates can ignore the fractional part. - </para> - <para> - The destination rectangle in CRTC coordinates is given by the - <parameter>crtc_x</parameter>, <parameter>crtc_y</parameter>, - <parameter>crtc_w</parameter> and <parameter>crtc_h</parameter> - parameters (as integer values). Devices scale the source rectangle to - the destination rectangle. If scaling is not supported, and the source - rectangle size doesn't match the destination rectangle size, the - driver must return a -<errorname>EINVAL</errorname> error. - </para> - </listitem> - <listitem> - <synopsis>int (*disable_plane)(struct drm_plane *plane);</synopsis> - <para> - Disable the plane. The DRM core calls this method in response to a - DRM_IOCTL_MODE_SETPLANE ioctl call with the frame buffer ID set to 0. - Disabled planes must not be processed by the CRTC. - </para> - </listitem> - <listitem> - <synopsis>void (*destroy)(struct drm_plane *plane);</synopsis> - <para> - Destroy the plane when not needed anymore. See - <xref linkend="drm-kms-init"/>. - </para> - </listitem> - </itemizedlist> - </sect3> - </sect2> - <sect2> - <title>Encoders (struct <structname>drm_encoder</structname>)</title> - <para> - An encoder takes pixel data from a CRTC and converts it to a format - suitable for any attached connectors. On some devices, it may be - possible to have a CRTC send data to more than one encoder. In that - case, both encoders would receive data from the same scanout buffer, - resulting in a "cloned" display configuration across the connectors - attached to each encoder. - </para> - <sect3> - <title>Encoder Initialization</title> - <para> - As for CRTCs, a KMS driver must create, initialize and register at - least one struct <structname>drm_encoder</structname> instance. The - instance is allocated and zeroed by the driver, possibly as part of a - larger structure. - </para> - <para> - Drivers must initialize the struct <structname>drm_encoder</structname> - <structfield>possible_crtcs</structfield> and - <structfield>possible_clones</structfield> fields before registering the - encoder. Both fields are bitmasks of respectively the CRTCs that the - encoder can be connected to, and sibling encoders candidate for cloning. - </para> - <para> - After being initialized, the encoder must be registered with a call to - <function>drm_encoder_init</function>. The function takes a pointer to - the encoder functions and an encoder type. Supported types are - <itemizedlist> - <listitem> - DRM_MODE_ENCODER_DAC for VGA and analog on DVI-I/DVI-A - </listitem> - <listitem> - DRM_MODE_ENCODER_TMDS for DVI, HDMI and (embedded) DisplayPort - </listitem> - <listitem> - DRM_MODE_ENCODER_LVDS for display panels - </listitem> - <listitem> - DRM_MODE_ENCODER_TVDAC for TV output (Composite, S-Video, Component, - SCART) - </listitem> - <listitem> - DRM_MODE_ENCODER_VIRTUAL for virtual machine displays - </listitem> - </itemizedlist> - </para> - <para> - Encoders must be attached to a CRTC to be used. DRM drivers leave - encoders unattached at initialization time. Applications (or the fbdev - compatibility layer when implemented) are responsible for attaching the - encoders they want to use to a CRTC. - </para> - </sect3> - <sect3> - <title>Encoder Operations</title> - <itemizedlist> - <listitem> - <synopsis>void (*destroy)(struct drm_encoder *encoder);</synopsis> - <para> - Called to destroy the encoder when not needed anymore. See - <xref linkend="drm-kms-init"/>. - </para> - </listitem> - <listitem> - <synopsis>void (*set_property)(struct drm_plane *plane, - struct drm_property *property, uint64_t value);</synopsis> - <para> - Set the value of the given plane property to - <parameter>value</parameter>. See <xref linkend="drm-kms-properties"/> - for more information about properties. - </para> - </listitem> - </itemizedlist> - </sect3> - </sect2> - <sect2> - <title>Connectors (struct <structname>drm_connector</structname>)</title> - <para> - A connector is the final destination for pixel data on a device, and - usually connects directly to an external display device like a monitor - or laptop panel. A connector can only be attached to one encoder at a - time. The connector is also the structure where information about the - attached display is kept, so it contains fields for display data, EDID - data, DPMS &amp; connection status, and information about modes - supported on the attached displays. - </para> - <sect3> - <title>Connector Initialization</title> - <para> - Finally a KMS driver must create, initialize, register and attach at - least one struct <structname>drm_connector</structname> instance. The - instance is created as other KMS objects and initialized by setting the - following fields. - </para> - <variablelist> - <varlistentry> - <term><structfield>interlace_allowed</structfield></term> - <listitem><para> - Whether the connector can handle interlaced modes. - </para></listitem> - </varlistentry> - <varlistentry> - <term><structfield>doublescan_allowed</structfield></term> - <listitem><para> - Whether the connector can handle doublescan. - </para></listitem> - </varlistentry> - <varlistentry> - <term><structfield>display_info - </structfield></term> - <listitem><para> - Display information is filled from EDID information when a display - is detected. For non hot-pluggable displays such as flat panels in - embedded systems, the driver should initialize the - <structfield>display_info</structfield>.<structfield>width_mm</structfield> - and - <structfield>display_info</structfield>.<structfield>height_mm</structfield> - fields with the physical size of the display. - </para></listitem> - </varlistentry> - <varlistentry> - <term id="drm-kms-connector-polled"><structfield>polled</structfield></term> - <listitem><para> - Connector polling mode, a combination of - <variablelist> - <varlistentry> - <term>DRM_CONNECTOR_POLL_HPD</term> - <listitem><para> - The connector generates hotplug events and doesn't need to be - periodically polled. The CONNECT and DISCONNECT flags must not - be set together with the HPD flag. - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRM_CONNECTOR_POLL_CONNECT</term> - <listitem><para> - Periodically poll the connector for connection. - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRM_CONNECTOR_POLL_DISCONNECT</term> - <listitem><para> - Periodically poll the connector for disconnection. - </para></listitem> - </varlistentry> - </variablelist> - Set to 0 for connectors that don't support connection status - discovery. - </para></listitem> - </varlistentry> - </variablelist> - <para> - The connector is then registered with a call to - <function>drm_connector_init</function> with a pointer to the connector - functions and a connector type, and exposed through sysfs with a call to - <function>drm_connector_register</function>. - </para> - <para> - Supported connector types are - <itemizedlist> - <listitem>DRM_MODE_CONNECTOR_VGA</listitem> - <listitem>DRM_MODE_CONNECTOR_DVII</listitem> - <listitem>DRM_MODE_CONNECTOR_DVID</listitem> - <listitem>DRM_MODE_CONNECTOR_DVIA</listitem> - <listitem>DRM_MODE_CONNECTOR_Composite</listitem> - <listitem>DRM_MODE_CONNECTOR_SVIDEO</listitem> - <listitem>DRM_MODE_CONNECTOR_LVDS</listitem> - <listitem>DRM_MODE_CONNECTOR_Component</listitem> - <listitem>DRM_MODE_CONNECTOR_9PinDIN</listitem> - <listitem>DRM_MODE_CONNECTOR_DisplayPort</listitem> - <listitem>DRM_MODE_CONNECTOR_HDMIA</listitem> - <listitem>DRM_MODE_CONNECTOR_HDMIB</listitem> - <listitem>DRM_MODE_CONNECTOR_TV</listitem> - <listitem>DRM_MODE_CONNECTOR_eDP</listitem> - <listitem>DRM_MODE_CONNECTOR_VIRTUAL</listitem> - </itemizedlist> - </para> - <para> - Connectors must be attached to an encoder to be used. For devices that - map connectors to encoders 1:1, the connector should be attached at - initialization time with a call to - <function>drm_mode_connector_attach_encoder</function>. The driver must - also set the <structname>drm_connector</structname> - <structfield>encoder</structfield> field to point to the attached - encoder. - </para> - <para> - Finally, drivers must initialize the connectors state change detection - with a call to <function>drm_kms_helper_poll_init</function>. If at - least one connector is pollable but can't generate hotplug interrupts - (indicated by the DRM_CONNECTOR_POLL_CONNECT and - DRM_CONNECTOR_POLL_DISCONNECT connector flags), a delayed work will - automatically be queued to periodically poll for changes. Connectors - that can generate hotplug interrupts must be marked with the - DRM_CONNECTOR_POLL_HPD flag instead, and their interrupt handler must - call <function>drm_helper_hpd_irq_event</function>. The function will - queue a delayed work to check the state of all connectors, but no - periodic polling will be done. - </para> - </sect3> - <sect3> - <title>Connector Operations</title> - <note><para> - Unless otherwise state, all operations are mandatory. - </para></note> - <sect4> - <title>DPMS</title> - <synopsis>void (*dpms)(struct drm_connector *connector, int mode);</synopsis> - <para> - The DPMS operation sets the power state of a connector. The mode - argument is one of - <itemizedlist> - <listitem><para>DRM_MODE_DPMS_ON</para></listitem> - <listitem><para>DRM_MODE_DPMS_STANDBY</para></listitem> - <listitem><para>DRM_MODE_DPMS_SUSPEND</para></listitem> - <listitem><para>DRM_MODE_DPMS_OFF</para></listitem> - </itemizedlist> - </para> - <para> - In all but DPMS_ON mode the encoder to which the connector is attached - should put the display in low-power mode by driving its signals - appropriately. If more than one connector is attached to the encoder - care should be taken not to change the power state of other displays as - a side effect. Low-power mode should be propagated to the encoders and - CRTCs when all related connectors are put in low-power mode. - </para> - </sect4> - <sect4> - <title>Modes</title> - <synopsis>int (*fill_modes)(struct drm_connector *connector, uint32_t max_width, - uint32_t max_height);</synopsis> - <para> - Fill the mode list with all supported modes for the connector. If the - <parameter>max_width</parameter> and <parameter>max_height</parameter> - arguments are non-zero, the implementation must ignore all modes wider - than <parameter>max_width</parameter> or higher than - <parameter>max_height</parameter>. - </para> - <para> - The connector must also fill in this operation its - <structfield>display_info</structfield> - <structfield>width_mm</structfield> and - <structfield>height_mm</structfield> fields with the connected display - physical size in millimeters. The fields should be set to 0 if the value - isn't known or is not applicable (for instance for projector devices). - </para> - </sect4> - <sect4> - <title>Connection Status</title> - <para> - The connection status is updated through polling or hotplug events when - supported (see <xref linkend="drm-kms-connector-polled"/>). The status - value is reported to userspace through ioctls and must not be used - inside the driver, as it only gets initialized by a call to - <function>drm_mode_getconnector</function> from userspace. - </para> - <synopsis>enum drm_connector_status (*detect)(struct drm_connector *connector, - bool force);</synopsis> - <para> - Check to see if anything is attached to the connector. The - <parameter>force</parameter> parameter is set to false whilst polling or - to true when checking the connector due to user request. - <parameter>force</parameter> can be used by the driver to avoid - expensive, destructive operations during automated probing. - </para> - <para> - Return connector_status_connected if something is connected to the - connector, connector_status_disconnected if nothing is connected and - connector_status_unknown if the connection state isn't known. - </para> - <para> - Drivers should only return connector_status_connected if the connection - status has really been probed as connected. Connectors that can't detect - the connection status, or failed connection status probes, should return - connector_status_unknown. - </para> - </sect4> - <sect4> - <title>Miscellaneous</title> - <itemizedlist> - <listitem> - <synopsis>void (*set_property)(struct drm_connector *connector, - struct drm_property *property, uint64_t value);</synopsis> - <para> - Set the value of the given connector property to - <parameter>value</parameter>. See <xref linkend="drm-kms-properties"/> - for more information about properties. - </para> - </listitem> - <listitem> - <synopsis>void (*destroy)(struct drm_connector *connector);</synopsis> - <para> - Destroy the connector when not needed anymore. See - <xref linkend="drm-kms-init"/>. - </para> - </listitem> - </itemizedlist> - </sect4> - </sect3> - </sect2> - <sect2> - <title>Cleanup</title> - <para> - The DRM core manages its objects' lifetime. When an object is not needed - anymore the core calls its destroy function, which must clean up and - free every resource allocated for the object. Every - <function>drm_*_init</function> call must be matched with a - corresponding <function>drm_*_cleanup</function> call to cleanup CRTCs - (<function>drm_crtc_cleanup</function>), planes - (<function>drm_plane_cleanup</function>), encoders - (<function>drm_encoder_cleanup</function>) and connectors - (<function>drm_connector_cleanup</function>). Furthermore, connectors - that have been added to sysfs must be removed by a call to - <function>drm_connector_unregister</function> before calling - <function>drm_connector_cleanup</function>. - </para> - <para> - Connectors state change detection must be cleanup up with a call to - <function>drm_kms_helper_poll_fini</function>. - </para> - </sect2> - <sect2> - <title>Output discovery and initialization example</title> - <programlisting><![CDATA[ -void intel_crt_init(struct drm_device *dev) -{ - struct drm_connector *connector; - struct intel_output *intel_output; - - intel_output = kzalloc(sizeof(struct intel_output), GFP_KERNEL); - if (!intel_output) - return; - - connector = &intel_output->base; - drm_connector_init(dev, &intel_output->base, - &intel_crt_connector_funcs, DRM_MODE_CONNECTOR_VGA); - - drm_encoder_init(dev, &intel_output->enc, &intel_crt_enc_funcs, - DRM_MODE_ENCODER_DAC); - - drm_mode_connector_attach_encoder(&intel_output->base, - &intel_output->enc); - - /* Set up the DDC bus. */ - intel_output->ddc_bus = intel_i2c_create(dev, GPIOA, "CRTDDC_A"); - if (!intel_output->ddc_bus) { - dev_printk(KERN_ERR, &dev->pdev->dev, "DDC bus registration " - "failed.\n"); - return; - } - - intel_output->type = INTEL_OUTPUT_ANALOG; - connector->interlace_allowed = 0; - connector->doublescan_allowed = 0; - - drm_encoder_helper_add(&intel_output->enc, &intel_crt_helper_funcs); - drm_connector_helper_add(connector, &intel_crt_connector_helper_funcs); - - drm_connector_register(connector); -}]]></programlisting> - <para> - In the example above (taken from the i915 driver), a CRTC, connector and - encoder combination is created. A device-specific i2c bus is also - created for fetching EDID data and performing monitor detection. Once - the process is complete, the new connector is registered with sysfs to - make its properties available to applications. - </para> - </sect2> - <sect2> - <title>KMS API Functions</title> -!Edrivers/gpu/drm/drm_crtc.c - </sect2> - <sect2> - <title>KMS Data Structures</title> -!Iinclude/drm/drm_crtc.h - </sect2> - <sect2> - <title>KMS Locking</title> -!Pdrivers/gpu/drm/drm_modeset_lock.c kms locking -!Iinclude/drm/drm_modeset_lock.h -!Edrivers/gpu/drm/drm_modeset_lock.c - </sect2> - </sect1> - - <!-- Internals: kms helper functions --> - - <sect1> - <title>Mode Setting Helper Functions</title> - <para> - The plane, CRTC, encoder and connector functions provided by the drivers - implement the DRM API. They're called by the DRM core and ioctl handlers - to handle device state changes and configuration request. As implementing - those functions often requires logic not specific to drivers, mid-layer - helper functions are available to avoid duplicating boilerplate code. - </para> - <para> - The DRM core contains one mid-layer implementation. The mid-layer provides - implementations of several plane, CRTC, encoder and connector functions - (called from the top of the mid-layer) that pre-process requests and call - lower-level functions provided by the driver (at the bottom of the - mid-layer). For instance, the - <function>drm_crtc_helper_set_config</function> function can be used to - fill the struct <structname>drm_crtc_funcs</structname> - <structfield>set_config</structfield> field. When called, it will split - the <methodname>set_config</methodname> operation in smaller, simpler - operations and call the driver to handle them. - </para> - <para> - To use the mid-layer, drivers call <function>drm_crtc_helper_add</function>, - <function>drm_encoder_helper_add</function> and - <function>drm_connector_helper_add</function> functions to install their - mid-layer bottom operations handlers, and fill the - <structname>drm_crtc_funcs</structname>, - <structname>drm_encoder_funcs</structname> and - <structname>drm_connector_funcs</structname> structures with pointers to - the mid-layer top API functions. Installing the mid-layer bottom operation - handlers is best done right after registering the corresponding KMS object. - </para> - <para> - The mid-layer is not split between CRTC, encoder and connector operations. - To use it, a driver must provide bottom functions for all of the three KMS - entities. - </para> - <sect2> - <title>Helper Functions</title> - <itemizedlist> - <listitem> - <synopsis>int drm_crtc_helper_set_config(struct drm_mode_set *set);</synopsis> - <para> - The <function>drm_crtc_helper_set_config</function> helper function - is a CRTC <methodname>set_config</methodname> implementation. It - first tries to locate the best encoder for each connector by calling - the connector <methodname>best_encoder</methodname> helper - operation. - </para> - <para> - After locating the appropriate encoders, the helper function will - call the <methodname>mode_fixup</methodname> encoder and CRTC helper - operations to adjust the requested mode, or reject it completely in - which case an error will be returned to the application. If the new - configuration after mode adjustment is identical to the current - configuration the helper function will return without performing any - other operation. - </para> - <para> - If the adjusted mode is identical to the current mode but changes to - the frame buffer need to be applied, the - <function>drm_crtc_helper_set_config</function> function will call - the CRTC <methodname>mode_set_base</methodname> helper operation. If - the adjusted mode differs from the current mode, or if the - <methodname>mode_set_base</methodname> helper operation is not - provided, the helper function performs a full mode set sequence by - calling the <methodname>prepare</methodname>, - <methodname>mode_set</methodname> and - <methodname>commit</methodname> CRTC and encoder helper operations, - in that order. - </para> - </listitem> - <listitem> - <synopsis>void drm_helper_connector_dpms(struct drm_connector *connector, int mode);</synopsis> - <para> - The <function>drm_helper_connector_dpms</function> helper function - is a connector <methodname>dpms</methodname> implementation that - tracks power state of connectors. To use the function, drivers must - provide <methodname>dpms</methodname> helper operations for CRTCs - and encoders to apply the DPMS state to the device. - </para> - <para> - The mid-layer doesn't track the power state of CRTCs and encoders. - The <methodname>dpms</methodname> helper operations can thus be - called with a mode identical to the currently active mode. - </para> - </listitem> - <listitem> - <synopsis>int drm_helper_probe_single_connector_modes(struct drm_connector *connector, - uint32_t maxX, uint32_t maxY);</synopsis> - <para> - The <function>drm_helper_probe_single_connector_modes</function> helper - function is a connector <methodname>fill_modes</methodname> - implementation that updates the connection status for the connector - and then retrieves a list of modes by calling the connector - <methodname>get_modes</methodname> helper operation. - </para> - <para> - If the helper operation returns no mode, and if the connector status - is connector_status_connected, standard VESA DMT modes up to - 1024x768 are automatically added to the modes list by a call to - <function>drm_add_modes_noedid</function>. - </para> - <para> - The function then filters out modes larger than - <parameter>max_width</parameter> and <parameter>max_height</parameter> - if specified. It finally calls the optional connector - <methodname>mode_valid</methodname> helper operation for each mode in - the probed list to check whether the mode is valid for the connector. - </para> - </listitem> - </itemizedlist> - </sect2> - <sect2> - <title>CRTC Helper Operations</title> - <itemizedlist> - <listitem id="drm-helper-crtc-mode-fixup"> - <synopsis>bool (*mode_fixup)(struct drm_crtc *crtc, - const struct drm_display_mode *mode, - struct drm_display_mode *adjusted_mode);</synopsis> - <para> - Let CRTCs adjust the requested mode or reject it completely. This - operation returns true if the mode is accepted (possibly after being - adjusted) or false if it is rejected. - </para> - <para> - The <methodname>mode_fixup</methodname> operation should reject the - mode if it can't reasonably use it. The definition of "reasonable" - is currently fuzzy in this context. One possible behaviour would be - to set the adjusted mode to the panel timings when a fixed-mode - panel is used with hardware capable of scaling. Another behaviour - would be to accept any input mode and adjust it to the closest mode - supported by the hardware (FIXME: This needs to be clarified). - </para> - </listitem> - <listitem> - <synopsis>int (*mode_set_base)(struct drm_crtc *crtc, int x, int y, - struct drm_framebuffer *old_fb)</synopsis> - <para> - Move the CRTC on the current frame buffer (stored in - <literal>crtc-&gt;fb</literal>) to position (x,y). Any of the frame - buffer, x position or y position may have been modified. - </para> - <para> - This helper operation is optional. If not provided, the - <function>drm_crtc_helper_set_config</function> function will fall - back to the <methodname>mode_set</methodname> helper operation. - </para> - <note><para> - FIXME: Why are x and y passed as arguments, as they can be accessed - through <literal>crtc-&gt;x</literal> and - <literal>crtc-&gt;y</literal>? - </para></note> - </listitem> - <listitem> - <synopsis>void (*prepare)(struct drm_crtc *crtc);</synopsis> - <para> - Prepare the CRTC for mode setting. This operation is called after - validating the requested mode. Drivers use it to perform - device-specific operations required before setting the new mode. - </para> - </listitem> - <listitem> - <synopsis>int (*mode_set)(struct drm_crtc *crtc, struct drm_display_mode *mode, - struct drm_display_mode *adjusted_mode, int x, int y, - struct drm_framebuffer *old_fb);</synopsis> - <para> - Set a new mode, position and frame buffer. Depending on the device - requirements, the mode can be stored internally by the driver and - applied in the <methodname>commit</methodname> operation, or - programmed to the hardware immediately. - </para> - <para> - The <methodname>mode_set</methodname> operation returns 0 on success - or a negative error code if an error occurs. - </para> - </listitem> - <listitem> - <synopsis>void (*commit)(struct drm_crtc *crtc);</synopsis> - <para> - Commit a mode. This operation is called after setting the new mode. - Upon return the device must use the new mode and be fully - operational. - </para> - </listitem> - </itemizedlist> - </sect2> - <sect2> - <title>Encoder Helper Operations</title> - <itemizedlist> - <listitem> - <synopsis>bool (*mode_fixup)(struct drm_encoder *encoder, - const struct drm_display_mode *mode, - struct drm_display_mode *adjusted_mode);</synopsis> - <para> - Let encoders adjust the requested mode or reject it completely. This - operation returns true if the mode is accepted (possibly after being - adjusted) or false if it is rejected. See the - <link linkend="drm-helper-crtc-mode-fixup">mode_fixup CRTC helper - operation</link> for an explanation of the allowed adjustments. - </para> - </listitem> - <listitem> - <synopsis>void (*prepare)(struct drm_encoder *encoder);</synopsis> - <para> - Prepare the encoder for mode setting. This operation is called after - validating the requested mode. Drivers use it to perform - device-specific operations required before setting the new mode. - </para> - </listitem> - <listitem> - <synopsis>void (*mode_set)(struct drm_encoder *encoder, - struct drm_display_mode *mode, - struct drm_display_mode *adjusted_mode);</synopsis> - <para> - Set a new mode. Depending on the device requirements, the mode can - be stored internally by the driver and applied in the - <methodname>commit</methodname> operation, or programmed to the - hardware immediately. - </para> - </listitem> - <listitem> - <synopsis>void (*commit)(struct drm_encoder *encoder);</synopsis> - <para> - Commit a mode. This operation is called after setting the new mode. - Upon return the device must use the new mode and be fully - operational. - </para> - </listitem> - </itemizedlist> - </sect2> - <sect2> - <title>Connector Helper Operations</title> - <itemizedlist> - <listitem> - <synopsis>struct drm_encoder *(*best_encoder)(struct drm_connector *connector);</synopsis> - <para> - Return a pointer to the best encoder for the connecter. Device that - map connectors to encoders 1:1 simply return the pointer to the - associated encoder. This operation is mandatory. - </para> - </listitem> - <listitem> - <synopsis>int (*get_modes)(struct drm_connector *connector);</synopsis> - <para> - Fill the connector's <structfield>probed_modes</structfield> list - by parsing EDID data with <function>drm_add_edid_modes</function>, - adding standard VESA DMT modes with <function>drm_add_modes_noedid</function>, - or calling <function>drm_mode_probed_add</function> directly for every - supported mode and return the number of modes it has detected. This - operation is mandatory. - </para> - <para> - Note that the caller function will automatically add standard VESA - DMT modes up to 1024x768 if the <methodname>get_modes</methodname> - helper operation returns no mode and if the connector status is - connector_status_connected. There is no need to call - <function>drm_add_edid_modes</function> manually in that case. - </para> - <para> - When adding modes manually the driver creates each mode with a call to - <function>drm_mode_create</function> and must fill the following fields. - <itemizedlist> - <listitem> - <synopsis>__u32 type;</synopsis> - <para> - Mode type bitmask, a combination of - <variablelist> - <varlistentry> - <term>DRM_MODE_TYPE_BUILTIN</term> - <listitem><para>not used?</para></listitem> - </varlistentry> - <varlistentry> - <term>DRM_MODE_TYPE_CLOCK_C</term> - <listitem><para>not used?</para></listitem> - </varlistentry> - <varlistentry> - <term>DRM_MODE_TYPE_CRTC_C</term> - <listitem><para>not used?</para></listitem> - </varlistentry> - <varlistentry> - <term> - DRM_MODE_TYPE_PREFERRED - The preferred mode for the connector - </term> - <listitem> - <para>not used?</para> - </listitem> - </varlistentry> - <varlistentry> - <term>DRM_MODE_TYPE_DEFAULT</term> - <listitem><para>not used?</para></listitem> - </varlistentry> - <varlistentry> - <term>DRM_MODE_TYPE_USERDEF</term> - <listitem><para>not used?</para></listitem> - </varlistentry> - <varlistentry> - <term>DRM_MODE_TYPE_DRIVER</term> - <listitem> - <para> - The mode has been created by the driver (as opposed to - to user-created modes). - </para> - </listitem> - </varlistentry> - </variablelist> - Drivers must set the DRM_MODE_TYPE_DRIVER bit for all modes they - create, and set the DRM_MODE_TYPE_PREFERRED bit for the preferred - mode. - </para> - </listitem> - <listitem> - <synopsis>__u32 clock;</synopsis> - <para>Pixel clock frequency in kHz unit</para> - </listitem> - <listitem> - <synopsis>__u16 hdisplay, hsync_start, hsync_end, htotal; - __u16 vdisplay, vsync_start, vsync_end, vtotal;</synopsis> - <para>Horizontal and vertical timing information</para> - <screen><![CDATA[ - Active Front Sync Back - Region Porch Porch - <-----------------------><----------------><-------------><--------------> - - //////////////////////| - ////////////////////// | - ////////////////////// |.................. ................ - _______________ - - <----- [hv]display -----> - <------------- [hv]sync_start ------------> - <--------------------- [hv]sync_end ---------------------> - <-------------------------------- [hv]total -----------------------------> -]]></screen> - </listitem> - <listitem> - <synopsis>__u16 hskew; - __u16 vscan;</synopsis> - <para>Unknown</para> - </listitem> - <listitem> - <synopsis>__u32 flags;</synopsis> - <para> - Mode flags, a combination of - <variablelist> - <varlistentry> - <term>DRM_MODE_FLAG_PHSYNC</term> - <listitem><para> - Horizontal sync is active high - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRM_MODE_FLAG_NHSYNC</term> - <listitem><para> - Horizontal sync is active low - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRM_MODE_FLAG_PVSYNC</term> - <listitem><para> - Vertical sync is active high - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRM_MODE_FLAG_NVSYNC</term> - <listitem><para> - Vertical sync is active low - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRM_MODE_FLAG_INTERLACE</term> - <listitem><para> - Mode is interlaced - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRM_MODE_FLAG_DBLSCAN</term> - <listitem><para> - Mode uses doublescan - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRM_MODE_FLAG_CSYNC</term> - <listitem><para> - Mode uses composite sync - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRM_MODE_FLAG_PCSYNC</term> - <listitem><para> - Composite sync is active high - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRM_MODE_FLAG_NCSYNC</term> - <listitem><para> - Composite sync is active low - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRM_MODE_FLAG_HSKEW</term> - <listitem><para> - hskew provided (not used?) - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRM_MODE_FLAG_BCAST</term> - <listitem><para> - not used? - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRM_MODE_FLAG_PIXMUX</term> - <listitem><para> - not used? - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRM_MODE_FLAG_DBLCLK</term> - <listitem><para> - not used? - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRM_MODE_FLAG_CLKDIV2</term> - <listitem><para> - ? - </para></listitem> - </varlistentry> - </variablelist> - </para> - <para> - Note that modes marked with the INTERLACE or DBLSCAN flags will be - filtered out by - <function>drm_helper_probe_single_connector_modes</function> if - the connector's <structfield>interlace_allowed</structfield> or - <structfield>doublescan_allowed</structfield> field is set to 0. - </para> - </listitem> - <listitem> - <synopsis>char name[DRM_DISPLAY_MODE_LEN];</synopsis> - <para> - Mode name. The driver must call - <function>drm_mode_set_name</function> to fill the mode name from - <structfield>hdisplay</structfield>, - <structfield>vdisplay</structfield> and interlace flag after - filling the corresponding fields. - </para> - </listitem> - </itemizedlist> - </para> - <para> - The <structfield>vrefresh</structfield> value is computed by - <function>drm_helper_probe_single_connector_modes</function>. - </para> - <para> - When parsing EDID data, <function>drm_add_edid_modes</function> fills the - connector <structfield>display_info</structfield> - <structfield>width_mm</structfield> and - <structfield>height_mm</structfield> fields. When creating modes - manually the <methodname>get_modes</methodname> helper operation must - set the <structfield>display_info</structfield> - <structfield>width_mm</structfield> and - <structfield>height_mm</structfield> fields if they haven't been set - already (for instance at initialization time when a fixed-size panel is - attached to the connector). The mode <structfield>width_mm</structfield> - and <structfield>height_mm</structfield> fields are only used internally - during EDID parsing and should not be set when creating modes manually. - </para> - </listitem> - <listitem> - <synopsis>int (*mode_valid)(struct drm_connector *connector, - struct drm_display_mode *mode);</synopsis> - <para> - Verify whether a mode is valid for the connector. Return MODE_OK for - supported modes and one of the enum drm_mode_status values (MODE_*) - for unsupported modes. This operation is optional. - </para> - <para> - As the mode rejection reason is currently not used beside for - immediately removing the unsupported mode, an implementation can - return MODE_BAD regardless of the exact reason why the mode is not - valid. - </para> - <note><para> - Note that the <methodname>mode_valid</methodname> helper operation is - only called for modes detected by the device, and - <emphasis>not</emphasis> for modes set by the user through the CRTC - <methodname>set_config</methodname> operation. - </para></note> - </listitem> - </itemizedlist> - </sect2> - <sect2> - <title>Atomic Modeset Helper Functions Reference</title> - <sect3> - <title>Overview</title> -!Pdrivers/gpu/drm/drm_atomic_helper.c overview - </sect3> - <sect3> - <title>Implementing Asynchronous Atomic Commit</title> -!Pdrivers/gpu/drm/drm_atomic_helper.c implementing async commit - </sect3> - <sect3> - <title>Atomic State Reset and Initialization</title> -!Pdrivers/gpu/drm/drm_atomic_helper.c atomic state reset and initialization - </sect3> -!Iinclude/drm/drm_atomic_helper.h -!Edrivers/gpu/drm/drm_atomic_helper.c - </sect2> - <sect2> - <title>Modeset Helper Functions Reference</title> -!Iinclude/drm/drm_crtc_helper.h -!Edrivers/gpu/drm/drm_crtc_helper.c -!Pdrivers/gpu/drm/drm_crtc_helper.c overview - </sect2> - <sect2> - <title>Output Probing Helper Functions Reference</title> -!Pdrivers/gpu/drm/drm_probe_helper.c output probing helper overview -!Edrivers/gpu/drm/drm_probe_helper.c - </sect2> - <sect2> - <title>fbdev Helper Functions Reference</title> -!Pdrivers/gpu/drm/drm_fb_helper.c fbdev helpers -!Edrivers/gpu/drm/drm_fb_helper.c -!Iinclude/drm/drm_fb_helper.h - </sect2> - <sect2> - <title>Display Port Helper Functions Reference</title> -!Pdrivers/gpu/drm/drm_dp_helper.c dp helpers -!Iinclude/drm/drm_dp_helper.h -!Edrivers/gpu/drm/drm_dp_helper.c - </sect2> - <sect2> - <title>Display Port MST Helper Functions Reference</title> -!Pdrivers/gpu/drm/drm_dp_mst_topology.c dp mst helper -!Iinclude/drm/drm_dp_mst_helper.h -!Edrivers/gpu/drm/drm_dp_mst_topology.c - </sect2> - <sect2> - <title>MIPI DSI Helper Functions Reference</title> -!Pdrivers/gpu/drm/drm_mipi_dsi.c dsi helpers -!Iinclude/drm/drm_mipi_dsi.h -!Edrivers/gpu/drm/drm_mipi_dsi.c - </sect2> - <sect2> - <title>EDID Helper Functions Reference</title> -!Edrivers/gpu/drm/drm_edid.c - </sect2> - <sect2> - <title>Rectangle Utilities Reference</title> -!Pinclude/drm/drm_rect.h rect utils -!Iinclude/drm/drm_rect.h -!Edrivers/gpu/drm/drm_rect.c - </sect2> - <sect2> - <title>Flip-work Helper Reference</title> -!Pinclude/drm/drm_flip_work.h flip utils -!Iinclude/drm/drm_flip_work.h -!Edrivers/gpu/drm/drm_flip_work.c - </sect2> - <sect2> - <title>HDMI Infoframes Helper Reference</title> - <para> - Strictly speaking this is not a DRM helper library but generally useable - by any driver interfacing with HDMI outputs like v4l or alsa drivers. - But it nicely fits into the overall topic of mode setting helper - libraries and hence is also included here. - </para> -!Iinclude/linux/hdmi.h -!Edrivers/video/hdmi.c - </sect2> - <sect2> - <title id="drm-kms-planehelpers">Plane Helper Reference</title> -!Edrivers/gpu/drm/drm_plane_helper.c -!Pdrivers/gpu/drm/drm_plane_helper.c overview - </sect2> - <sect2> - <title>Tile group</title> -!Pdrivers/gpu/drm/drm_crtc.c Tile group - </sect2> - <sect2> - <title>Bridges</title> - <sect3> - <title>Overview</title> -!Pdrivers/gpu/drm/drm_bridge.c overview - </sect3> - <sect3> - <title>Default bridge callback sequence</title> -!Pdrivers/gpu/drm/drm_bridge.c bridge callbacks - </sect3> -!Edrivers/gpu/drm/drm_bridge.c - </sect2> - </sect1> - - <!-- Internals: kms properties --> - - <sect1 id="drm-kms-properties"> - <title>KMS Properties</title> - <para> - Drivers may need to expose additional parameters to applications than - those described in the previous sections. KMS supports attaching - properties to CRTCs, connectors and planes and offers a userspace API to - list, get and set the property values. - </para> - <para> - Properties are identified by a name that uniquely defines the property - purpose, and store an associated value. For all property types except blob - properties the value is a 64-bit unsigned integer. - </para> - <para> - KMS differentiates between properties and property instances. Drivers - first create properties and then create and associate individual instances - of those properties to objects. A property can be instantiated multiple - times and associated with different objects. Values are stored in property - instances, and all other property information are stored in the property - and shared between all instances of the property. - </para> - <para> - Every property is created with a type that influences how the KMS core - handles the property. Supported property types are - <variablelist> - <varlistentry> - <term>DRM_MODE_PROP_RANGE</term> - <listitem><para>Range properties report their minimum and maximum - admissible values. The KMS core verifies that values set by - application fit in that range.</para></listitem> - </varlistentry> - <varlistentry> - <term>DRM_MODE_PROP_ENUM</term> - <listitem><para>Enumerated properties take a numerical value that - ranges from 0 to the number of enumerated values defined by the - property minus one, and associate a free-formed string name to each - value. Applications can retrieve the list of defined value-name pairs - and use the numerical value to get and set property instance values. - </para></listitem> - </varlistentry> - <varlistentry> - <term>DRM_MODE_PROP_BITMASK</term> - <listitem><para>Bitmask properties are enumeration properties that - additionally restrict all enumerated values to the 0..63 range. - Bitmask property instance values combine one or more of the - enumerated bits defined by the property.</para></listitem> - </varlistentry> - <varlistentry> - <term>DRM_MODE_PROP_BLOB</term> - <listitem><para>Blob properties store a binary blob without any format - restriction. The binary blobs are created as KMS standalone objects, - and blob property instance values store the ID of their associated - blob object.</para> - <para>Blob properties are only used for the connector EDID property - and cannot be created by drivers.</para></listitem> - </varlistentry> - </variablelist> - </para> - <para> - To create a property drivers call one of the following functions depending - on the property type. All property creation functions take property flags - and name, as well as type-specific arguments. - <itemizedlist> - <listitem> - <synopsis>struct drm_property *drm_property_create_range(struct drm_device *dev, int flags, - const char *name, - uint64_t min, uint64_t max);</synopsis> - <para>Create a range property with the given minimum and maximum - values.</para> - </listitem> - <listitem> - <synopsis>struct drm_property *drm_property_create_enum(struct drm_device *dev, int flags, - const char *name, - const struct drm_prop_enum_list *props, - int num_values);</synopsis> - <para>Create an enumerated property. The <parameter>props</parameter> - argument points to an array of <parameter>num_values</parameter> - value-name pairs.</para> - </listitem> - <listitem> - <synopsis>struct drm_property *drm_property_create_bitmask(struct drm_device *dev, - int flags, const char *name, - const struct drm_prop_enum_list *props, - int num_values);</synopsis> - <para>Create a bitmask property. The <parameter>props</parameter> - argument points to an array of <parameter>num_values</parameter> - value-name pairs.</para> - </listitem> - </itemizedlist> - </para> - <para> - Properties can additionally be created as immutable, in which case they - will be read-only for applications but can be modified by the driver. To - create an immutable property drivers must set the DRM_MODE_PROP_IMMUTABLE - flag at property creation time. - </para> - <para> - When no array of value-name pairs is readily available at property - creation time for enumerated or range properties, drivers can create - the property using the <function>drm_property_create</function> function - and manually add enumeration value-name pairs by calling the - <function>drm_property_add_enum</function> function. Care must be taken to - properly specify the property type through the <parameter>flags</parameter> - argument. - </para> - <para> - After creating properties drivers can attach property instances to CRTC, - connector and plane objects by calling the - <function>drm_object_attach_property</function>. The function takes a - pointer to the target object, a pointer to the previously created property - and an initial instance value. - </para> - <sect2> - <title>Existing KMS Properties</title> - <para> - The following table gives description of drm properties exposed by various - modules/drivers. - </para> - <table border="1" cellpadding="0" cellspacing="0"> - <tbody> - <tr style="font-weight: bold;"> - <td valign="top" >Owner Module/Drivers</td> - <td valign="top" >Group</td> - <td valign="top" >Property Name</td> - <td valign="top" >Type</td> - <td valign="top" >Property Values</td> - <td valign="top" >Object attached</td> - <td valign="top" >Description/Restrictions</td> - </tr> - <tr> - <td rowspan="37" valign="top" >DRM</td> - <td valign="top" >Generic</td> - <td valign="top" >“rotation”</td> - <td valign="top" >BITMASK</td> - <td valign="top" >{ 0, "rotate-0" }, - { 1, "rotate-90" }, - { 2, "rotate-180" }, - { 3, "rotate-270" }, - { 4, "reflect-x" }, - { 5, "reflect-y" }</td> - <td valign="top" >CRTC, Plane</td> - <td valign="top" >rotate-(degrees) rotates the image by the specified amount in degrees - in counter clockwise direction. reflect-x and reflect-y reflects the - image along the specified axis prior to rotation</td> - </tr> - <tr> - <td rowspan="5" valign="top" >Connector</td> - <td valign="top" >“EDID”</td> - <td valign="top" >BLOB | IMMUTABLE</td> - <td valign="top" >0</td> - <td valign="top" >Connector</td> - <td valign="top" >Contains id of edid blob ptr object.</td> - </tr> - <tr> - <td valign="top" >“DPMS”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ “On”, “Standby”, “Suspend”, “Off” }</td> - <td valign="top" >Connector</td> - <td valign="top" >Contains DPMS operation mode value.</td> - </tr> - <tr> - <td valign="top" >“PATH”</td> - <td valign="top" >BLOB | IMMUTABLE</td> - <td valign="top" >0</td> - <td valign="top" >Connector</td> - <td valign="top" >Contains topology path to a connector.</td> - </tr> - <tr> - <td valign="top" >“TILE”</td> - <td valign="top" >BLOB | IMMUTABLE</td> - <td valign="top" >0</td> - <td valign="top" >Connector</td> - <td valign="top" >Contains tiling information for a connector.</td> - </tr> - <tr> - <td valign="top" >“CRTC_ID”</td> - <td valign="top" >OBJECT</td> - <td valign="top" >DRM_MODE_OBJECT_CRTC</td> - <td valign="top" >Connector</td> - <td valign="top" >CRTC that connector is attached to (atomic)</td> - </tr> - <tr> - <td rowspan="11" valign="top" >Plane</td> - <td valign="top" >“type”</td> - <td valign="top" >ENUM | IMMUTABLE</td> - <td valign="top" >{ "Overlay", "Primary", "Cursor" }</td> - <td valign="top" >Plane</td> - <td valign="top" >Plane type</td> - </tr> - <tr> - <td valign="top" >“SRC_X”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=UINT_MAX</td> - <td valign="top" >Plane</td> - <td valign="top" >Scanout source x coordinate in 16.16 fixed point (atomic)</td> - </tr> - <tr> - <td valign="top" >“SRC_Y”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=UINT_MAX</td> - <td valign="top" >Plane</td> - <td valign="top" >Scanout source y coordinate in 16.16 fixed point (atomic)</td> - </tr> - <tr> - <td valign="top" >“SRC_W”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=UINT_MAX</td> - <td valign="top" >Plane</td> - <td valign="top" >Scanout source width in 16.16 fixed point (atomic)</td> - </tr> - <tr> - <td valign="top" >“SRC_H”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=UINT_MAX</td> - <td valign="top" >Plane</td> - <td valign="top" >Scanout source height in 16.16 fixed point (atomic)</td> - </tr> - <tr> - <td valign="top" >“CRTC_X”</td> - <td valign="top" >SIGNED_RANGE</td> - <td valign="top" >Min=INT_MIN, Max=INT_MAX</td> - <td valign="top" >Plane</td> - <td valign="top" >Scanout CRTC (destination) x coordinate (atomic)</td> - </tr> - <tr> - <td valign="top" >“CRTC_Y”</td> - <td valign="top" >SIGNED_RANGE</td> - <td valign="top" >Min=INT_MIN, Max=INT_MAX</td> - <td valign="top" >Plane</td> - <td valign="top" >Scanout CRTC (destination) y coordinate (atomic)</td> - </tr> - <tr> - <td valign="top" >“CRTC_W”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=UINT_MAX</td> - <td valign="top" >Plane</td> - <td valign="top" >Scanout CRTC (destination) width (atomic)</td> - </tr> - <tr> - <td valign="top" >“CRTC_H”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=UINT_MAX</td> - <td valign="top" >Plane</td> - <td valign="top" >Scanout CRTC (destination) height (atomic)</td> - </tr> - <tr> - <td valign="top" >“FB_ID”</td> - <td valign="top" >OBJECT</td> - <td valign="top" >DRM_MODE_OBJECT_FB</td> - <td valign="top" >Plane</td> - <td valign="top" >Scanout framebuffer (atomic)</td> - </tr> - <tr> - <td valign="top" >“CRTC_ID”</td> - <td valign="top" >OBJECT</td> - <td valign="top" >DRM_MODE_OBJECT_CRTC</td> - <td valign="top" >Plane</td> - <td valign="top" >CRTC that plane is attached to (atomic)</td> - </tr> - <tr> - <td rowspan="2" valign="top" >DVI-I</td> - <td valign="top" >“subconnector”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ “Unknown”, “DVI-D”, “DVI-A” }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“select subconnector”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ “Automatic”, “DVI-D”, “DVI-A” }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="13" valign="top" >TV</td> - <td valign="top" >“subconnector”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "Unknown", "Composite", "SVIDEO", "Component", "SCART" }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“select subconnector”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "Automatic", "Composite", "SVIDEO", "Component", "SCART" }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“mode”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "NTSC_M", "NTSC_J", "NTSC_443", "PAL_B" } etc.</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“left margin”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=100</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“right margin”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=100</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“top margin”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=100</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“bottom margin”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=100</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“brightness”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=100</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“contrast”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=100</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“flicker reduction”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=100</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“overscan”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=100</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“saturation”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=100</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“hue”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=100</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="2" valign="top" >Virtual GPU</td> - <td valign="top" >“suggested X”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=0xffffffff</td> - <td valign="top" >Connector</td> - <td valign="top" >property to suggest an X offset for a connector</td> - </tr> - <tr> - <td valign="top" >“suggested Y”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=0xffffffff</td> - <td valign="top" >Connector</td> - <td valign="top" >property to suggest an Y offset for a connector</td> - </tr> - <tr> - <td rowspan="3" valign="top" >Optional</td> - <td valign="top" >“scaling mode”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "None", "Full", "Center", "Full aspect" }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"aspect ratio"</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "None", "4:3", "16:9" }</td> - <td valign="top" >Connector</td> - <td valign="top" >DRM property to set aspect ratio from user space app. - This enum is made generic to allow addition of custom aspect - ratios.</td> - </tr> - <tr> - <td valign="top" >“dirty”</td> - <td valign="top" >ENUM | IMMUTABLE</td> - <td valign="top" >{ "Off", "On", "Annotate" }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="20" valign="top" >i915</td> - <td rowspan="2" valign="top" >Generic</td> - <td valign="top" >"Broadcast RGB"</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "Automatic", "Full", "Limited 16:235" }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“audio”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "force-dvi", "off", "auto", "on" }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="17" valign="top" >SDVO-TV</td> - <td valign="top" >“mode”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "NTSC_M", "NTSC_J", "NTSC_443", "PAL_B" } etc.</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"left_margin"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"right_margin"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"top_margin"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"bottom_margin"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“hpos”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“vpos”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“contrast”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“saturation”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“hue”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“sharpness”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“flicker_filter”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“flicker_filter_adaptive”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“flicker_filter_2d”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“tv_chroma_filter”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“tv_luma_filter”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“dot_crawl”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=1</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >SDVO-TV/LVDS</td> - <td valign="top" >“brightness”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="2" valign="top" >CDV gma-500</td> - <td rowspan="2" valign="top" >Generic</td> - <td valign="top" >"Broadcast RGB"</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ “Full”, “Limited 16:235” }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"Broadcast RGB"</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ “off”, “auto”, “on” }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="19" valign="top" >Poulsbo</td> - <td rowspan="1" valign="top" >Generic</td> - <td valign="top" >“backlight”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=100</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="17" valign="top" >SDVO-TV</td> - <td valign="top" >“mode”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "NTSC_M", "NTSC_J", "NTSC_443", "PAL_B" } etc.</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"left_margin"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"right_margin"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"top_margin"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"bottom_margin"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“hpos”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“vpos”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“contrast”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“saturation”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“hue”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“sharpness”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“flicker_filter”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“flicker_filter_adaptive”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“flicker_filter_2d”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“tv_chroma_filter”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“tv_luma_filter”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“dot_crawl”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=1</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >SDVO-TV/LVDS</td> - <td valign="top" >“brightness”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max= SDVO dependent</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="11" valign="top" >armada</td> - <td rowspan="2" valign="top" >CRTC</td> - <td valign="top" >"CSC_YUV"</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "Auto" , "CCIR601", "CCIR709" }</td> - <td valign="top" >CRTC</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"CSC_RGB"</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "Auto", "Computer system", "Studio" }</td> - <td valign="top" >CRTC</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="9" valign="top" >Overlay</td> - <td valign="top" >"colorkey"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=0xffffff</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"colorkey_min"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=0xffffff</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"colorkey_max"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=0xffffff</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"colorkey_val"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=0xffffff</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"colorkey_alpha"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=0xffffff</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"colorkey_mode"</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "disabled", "Y component", "U component" - , "V component", "RGB", “R component", "G component", "B component" }</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"brightness"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=256 + 255</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"contrast"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=0x7fff</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"saturation"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=0x7fff</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="2" valign="top" >exynos</td> - <td valign="top" >CRTC</td> - <td valign="top" >“mode”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "normal", "blank" }</td> - <td valign="top" >CRTC</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >Overlay</td> - <td valign="top" >“zpos”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=MAX_PLANE-1</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="2" valign="top" >i2c/ch7006_drv</td> - <td valign="top" >Generic</td> - <td valign="top" >“scale”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=2</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="1" valign="top" >TV</td> - <td valign="top" >“mode”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "PAL", "PAL-M","PAL-N"}, ”PAL-Nc" - , "PAL-60", "NTSC-M", "NTSC-J" }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="15" valign="top" >nouveau</td> - <td rowspan="6" valign="top" >NV10 Overlay</td> - <td valign="top" >"colorkey"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=0x01ffffff</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“contrast”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=8192-1</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“brightness”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=1024</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“hue”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=359</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“saturation”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=8192-1</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“iturbt_709”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=1</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="2" valign="top" >Nv04 Overlay</td> - <td valign="top" >“colorkey”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=0x01ffffff</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“brightness”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=1024</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="7" valign="top" >Display</td> - <td valign="top" >“dithering mode”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "auto", "off", "on" }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“dithering depth”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "auto", "off", "on", "static 2x2", "dynamic 2x2", "temporal" }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“underscan”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "auto", "6 bpc", "8 bpc" }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“underscan hborder”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=128</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“underscan vborder”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=128</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“vibrant hue”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=180</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >“color vibrance”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=200</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >omap</td> - <td valign="top" >Generic</td> - <td valign="top" >“zorder”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=3</td> - <td valign="top" >CRTC, Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >qxl</td> - <td valign="top" >Generic</td> - <td valign="top" >“hotplug_mode_update"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=1</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="9" valign="top" >radeon</td> - <td valign="top" >DVI-I</td> - <td valign="top" >“coherent”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=1</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >DAC enable load detect</td> - <td valign="top" >“load detection”</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=1</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >TV Standard</td> - <td valign="top" >"tv standard"</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "ntsc", "pal", "pal-m", "pal-60", "ntsc-j" - , "scart-pal", "pal-cn", "secam" }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >legacy TMDS PLL detect</td> - <td valign="top" >"tmds_pll"</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "driver", "bios" }</td> - <td valign="top" >-</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="3" valign="top" >Underscan</td> - <td valign="top" >"underscan"</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "off", "on", "auto" }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"underscan hborder"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=128</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"underscan vborder"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=128</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >Audio</td> - <td valign="top" >“audio”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "off", "on", "auto" }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >FMT Dithering</td> - <td valign="top" >“dither”</td> - <td valign="top" >ENUM</td> - <td valign="top" >{ "off", "on" }</td> - <td valign="top" >Connector</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td rowspan="3" valign="top" >rcar-du</td> - <td rowspan="3" valign="top" >Generic</td> - <td valign="top" >"alpha"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=255</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"colorkey"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=0, Max=0x01ffffff</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - <tr> - <td valign="top" >"zpos"</td> - <td valign="top" >RANGE</td> - <td valign="top" >Min=1, Max=7</td> - <td valign="top" >Plane</td> - <td valign="top" >TBD</td> - </tr> - </tbody> - </table> - </sect2> - </sect1> - - <!-- Internals: vertical blanking --> - - <sect1 id="drm-vertical-blank"> - <title>Vertical Blanking</title> - <para> - Vertical blanking plays a major role in graphics rendering. To achieve - tear-free display, users must synchronize page flips and/or rendering to - vertical blanking. The DRM API offers ioctls to perform page flips - synchronized to vertical blanking and wait for vertical blanking. - </para> - <para> - The DRM core handles most of the vertical blanking management logic, which - involves filtering out spurious interrupts, keeping race-free blanking - counters, coping with counter wrap-around and resets and keeping use - counts. It relies on the driver to generate vertical blanking interrupts - and optionally provide a hardware vertical blanking counter. Drivers must - implement the following operations. - </para> - <itemizedlist> - <listitem> - <synopsis>int (*enable_vblank) (struct drm_device *dev, int crtc); -void (*disable_vblank) (struct drm_device *dev, int crtc);</synopsis> - <para> - Enable or disable vertical blanking interrupts for the given CRTC. - </para> - </listitem> - <listitem> - <synopsis>u32 (*get_vblank_counter) (struct drm_device *dev, int crtc);</synopsis> - <para> - Retrieve the value of the vertical blanking counter for the given - CRTC. If the hardware maintains a vertical blanking counter its value - should be returned. Otherwise drivers can use the - <function>drm_vblank_count</function> helper function to handle this - operation. - </para> - </listitem> - </itemizedlist> - <para> - Drivers must initialize the vertical blanking handling core with a call to - <function>drm_vblank_init</function> in their - <methodname>load</methodname> operation. The function will set the struct - <structname>drm_device</structname> - <structfield>vblank_disable_allowed</structfield> field to 0. This will - keep vertical blanking interrupts enabled permanently until the first mode - set operation, where <structfield>vblank_disable_allowed</structfield> is - set to 1. The reason behind this is not clear. Drivers can set the field - to 1 after <function>calling drm_vblank_init</function> to make vertical - blanking interrupts dynamically managed from the beginning. - </para> - <para> - Vertical blanking interrupts can be enabled by the DRM core or by drivers - themselves (for instance to handle page flipping operations). The DRM core - maintains a vertical blanking use count to ensure that the interrupts are - not disabled while a user still needs them. To increment the use count, - drivers call <function>drm_vblank_get</function>. Upon return vertical - blanking interrupts are guaranteed to be enabled. - </para> - <para> - To decrement the use count drivers call - <function>drm_vblank_put</function>. Only when the use count drops to zero - will the DRM core disable the vertical blanking interrupts after a delay - by scheduling a timer. The delay is accessible through the vblankoffdelay - module parameter or the <varname>drm_vblank_offdelay</varname> global - variable and expressed in milliseconds. Its default value is 5000 ms. - Zero means never disable, and a negative value means disable immediately. - Drivers may override the behaviour by setting the - <structname>drm_device</structname> - <structfield>vblank_disable_immediate</structfield> flag, which when set - causes vblank interrupts to be disabled immediately regardless of the - drm_vblank_offdelay value. The flag should only be set if there's a - properly working hardware vblank counter present. - </para> - <para> - When a vertical blanking interrupt occurs drivers only need to call the - <function>drm_handle_vblank</function> function to account for the - interrupt. - </para> - <para> - Resources allocated by <function>drm_vblank_init</function> must be freed - with a call to <function>drm_vblank_cleanup</function> in the driver - <methodname>unload</methodname> operation handler. - </para> - <sect2> - <title>Vertical Blanking and Interrupt Handling Functions Reference</title> -!Edrivers/gpu/drm/drm_irq.c -!Finclude/drm/drmP.h drm_crtc_vblank_waitqueue - </sect2> - </sect1> - - <!-- Internals: open/close, file operations and ioctls --> - - <sect1> - <title>Open/Close, File Operations and IOCTLs</title> - <sect2> - <title>Open and Close</title> - <synopsis>int (*firstopen) (struct drm_device *); -void (*lastclose) (struct drm_device *); -int (*open) (struct drm_device *, struct drm_file *); -void (*preclose) (struct drm_device *, struct drm_file *); -void (*postclose) (struct drm_device *, struct drm_file *);</synopsis> - <abstract>Open and close handlers. None of those methods are mandatory. - </abstract> - <para> - The <methodname>firstopen</methodname> method is called by the DRM core - for legacy UMS (User Mode Setting) drivers only when an application - opens a device that has no other opened file handle. UMS drivers can - implement it to acquire device resources. KMS drivers can't use the - method and must acquire resources in the <methodname>load</methodname> - method instead. - </para> - <para> - Similarly the <methodname>lastclose</methodname> method is called when - the last application holding a file handle opened on the device closes - it, for both UMS and KMS drivers. Additionally, the method is also - called at module unload time or, for hot-pluggable devices, when the - device is unplugged. The <methodname>firstopen</methodname> and - <methodname>lastclose</methodname> calls can thus be unbalanced. - </para> - <para> - The <methodname>open</methodname> method is called every time the device - is opened by an application. Drivers can allocate per-file private data - in this method and store them in the struct - <structname>drm_file</structname> <structfield>driver_priv</structfield> - field. Note that the <methodname>open</methodname> method is called - before <methodname>firstopen</methodname>. - </para> - <para> - The close operation is split into <methodname>preclose</methodname> and - <methodname>postclose</methodname> methods. Drivers must stop and - cleanup all per-file operations in the <methodname>preclose</methodname> - method. For instance pending vertical blanking and page flip events must - be cancelled. No per-file operation is allowed on the file handle after - returning from the <methodname>preclose</methodname> method. - </para> - <para> - Finally the <methodname>postclose</methodname> method is called as the - last step of the close operation, right before calling the - <methodname>lastclose</methodname> method if no other open file handle - exists for the device. Drivers that have allocated per-file private data - in the <methodname>open</methodname> method should free it here. - </para> - <para> - The <methodname>lastclose</methodname> method should restore CRTC and - plane properties to default value, so that a subsequent open of the - device will not inherit state from the previous user. It can also be - used to execute delayed power switching state changes, e.g. in - conjunction with the vga_switcheroo infrastructure. Beyond that KMS - drivers should not do any further cleanup. Only legacy UMS drivers might - need to clean up device state so that the vga console or an independent - fbdev driver could take over. - </para> - </sect2> - <sect2> - <title>File Operations</title> - <synopsis>const struct file_operations *fops</synopsis> - <abstract>File operations for the DRM device node.</abstract> - <para> - Drivers must define the file operations structure that forms the DRM - userspace API entry point, even though most of those operations are - implemented in the DRM core. The <methodname>open</methodname>, - <methodname>release</methodname> and <methodname>ioctl</methodname> - operations are handled by - <programlisting> - .owner = THIS_MODULE, - .open = drm_open, - .release = drm_release, - .unlocked_ioctl = drm_ioctl, - #ifdef CONFIG_COMPAT - .compat_ioctl = drm_compat_ioctl, - #endif - </programlisting> - </para> - <para> - Drivers that implement private ioctls that requires 32/64bit - compatibility support must provide their own - <methodname>compat_ioctl</methodname> handler that processes private - ioctls and calls <function>drm_compat_ioctl</function> for core ioctls. - </para> - <para> - The <methodname>read</methodname> and <methodname>poll</methodname> - operations provide support for reading DRM events and polling them. They - are implemented by - <programlisting> - .poll = drm_poll, - .read = drm_read, - .llseek = no_llseek, - </programlisting> - </para> - <para> - The memory mapping implementation varies depending on how the driver - manages memory. Pre-GEM drivers will use <function>drm_mmap</function>, - while GEM-aware drivers will use <function>drm_gem_mmap</function>. See - <xref linkend="drm-gem"/>. - <programlisting> - .mmap = drm_gem_mmap, - </programlisting> - </para> - <para> - No other file operation is supported by the DRM API. - </para> - </sect2> - <sect2> - <title>IOCTLs</title> - <synopsis>struct drm_ioctl_desc *ioctls; -int num_ioctls;</synopsis> - <abstract>Driver-specific ioctls descriptors table.</abstract> - <para> - Driver-specific ioctls numbers start at DRM_COMMAND_BASE. The ioctls - descriptors table is indexed by the ioctl number offset from the base - value. Drivers can use the DRM_IOCTL_DEF_DRV() macro to initialize the - table entries. - </para> - <para> - <programlisting>DRM_IOCTL_DEF_DRV(ioctl, func, flags)</programlisting> - <para> - <parameter>ioctl</parameter> is the ioctl name. Drivers must define - the DRM_##ioctl and DRM_IOCTL_##ioctl macros to the ioctl number - offset from DRM_COMMAND_BASE and the ioctl number respectively. The - first macro is private to the device while the second must be exposed - to userspace in a public header. - </para> - <para> - <parameter>func</parameter> is a pointer to the ioctl handler function - compatible with the <type>drm_ioctl_t</type> type. - <programlisting>typedef int drm_ioctl_t(struct drm_device *dev, void *data, - struct drm_file *file_priv);</programlisting> - </para> - <para> - <parameter>flags</parameter> is a bitmask combination of the following - values. It restricts how the ioctl is allowed to be called. - <itemizedlist> - <listitem><para> - DRM_AUTH - Only authenticated callers allowed - </para></listitem> - <listitem><para> - DRM_MASTER - The ioctl can only be called on the master file - handle - </para></listitem> - <listitem><para> - DRM_ROOT_ONLY - Only callers with the SYSADMIN capability allowed - </para></listitem> - <listitem><para> - DRM_CONTROL_ALLOW - The ioctl can only be called on a control - device - </para></listitem> - <listitem><para> - DRM_UNLOCKED - The ioctl handler will be called without locking - the DRM global mutex - </para></listitem> - </itemizedlist> - </para> - </para> - </sect2> - </sect1> - <sect1> - <title>Legacy Support Code</title> - <para> - The section very briefly covers some of the old legacy support code which - is only used by old DRM drivers which have done a so-called shadow-attach - to the underlying device instead of registering as a real driver. This - also includes some of the old generic buffer management and command - submission code. Do not use any of this in new and modern drivers. - </para> - - <sect2> - <title>Legacy Suspend/Resume</title> - <para> - The DRM core provides some suspend/resume code, but drivers wanting full - suspend/resume support should provide save() and restore() functions. - These are called at suspend, hibernate, or resume time, and should perform - any state save or restore required by your device across suspend or - hibernate states. - </para> - <synopsis>int (*suspend) (struct drm_device *, pm_message_t state); - int (*resume) (struct drm_device *);</synopsis> - <para> - Those are legacy suspend and resume methods which - <emphasis>only</emphasis> work with the legacy shadow-attach driver - registration functions. New driver should use the power management - interface provided by their bus type (usually through - the struct <structname>device_driver</structname> dev_pm_ops) and set - these methods to NULL. - </para> - </sect2> - - <sect2> - <title>Legacy DMA Services</title> - <para> - This should cover how DMA mapping etc. is supported by the core. - These functions are deprecated and should not be used. - </para> - </sect2> - </sect1> - </chapter> - -<!-- TODO - -- Add a glossary -- Document the struct_mutex catch-all lock -- Document connector properties - -- Why is the load method optional? -- What are drivers supposed to set the initial display state to, and how? - Connector's DPMS states are not initialized and are thus equal to - DRM_MODE_DPMS_ON. The fbcon compatibility layer calls - drm_helper_disable_unused_functions(), which disables unused encoders and - CRTCs, but doesn't touch the connectors' DPMS state, and - drm_helper_connector_dpms() in reaction to fbdev blanking events. Do drivers - that don't implement (or just don't use) fbcon compatibility need to call - those functions themselves? -- vblank_disable_allowed is set to 1 in the first drm_vblank_post_modeset() - call and never set back to 0. It seems to be safe to permanently set it to 1 - in drm_vblank_init() for KMS driver, and it might be safe for UMS drivers as - well. This should be investigated. -- crtc and connector .save and .restore operations are only used internally in - drivers, should they be removed from the core? -- encoder mid-layer .save and .restore operations are only used internally in - drivers, should they be removed from the core? -- encoder mid-layer .detect operation is only used internally in drivers, - should it be removed from the core? ---> - - <!-- External interfaces --> - - <chapter id="drmExternals"> - <title>Userland interfaces</title> - <para> - The DRM core exports several interfaces to applications, - generally intended to be used through corresponding libdrm - wrapper functions. In addition, drivers export device-specific - interfaces for use by userspace drivers &amp; device-aware - applications through ioctls and sysfs files. - </para> - <para> - External interfaces include: memory mapping, context management, - DMA operations, AGP management, vblank control, fence - management, memory management, and output management. - </para> - <para> - Cover generic ioctls and sysfs layout here. We only need high-level - info, since man pages should cover the rest. - </para> - - <!-- External: render nodes --> - - <sect1> - <title>Render nodes</title> - <para> - DRM core provides multiple character-devices for user-space to use. - Depending on which device is opened, user-space can perform a different - set of operations (mainly ioctls). The primary node is always created - and called card&lt;num&gt;. Additionally, a currently - unused control node, called controlD&lt;num&gt; is also - created. The primary node provides all legacy operations and - historically was the only interface used by userspace. With KMS, the - control node was introduced. However, the planned KMS control interface - has never been written and so the control node stays unused to date. - </para> - <para> - With the increased use of offscreen renderers and GPGPU applications, - clients no longer require running compositors or graphics servers to - make use of a GPU. But the DRM API required unprivileged clients to - authenticate to a DRM-Master prior to getting GPU access. To avoid this - step and to grant clients GPU access without authenticating, render - nodes were introduced. Render nodes solely serve render clients, that - is, no modesetting or privileged ioctls can be issued on render nodes. - Only non-global rendering commands are allowed. If a driver supports - render nodes, it must advertise it via the DRIVER_RENDER - DRM driver capability. If not supported, the primary node must be used - for render clients together with the legacy drmAuth authentication - procedure. - </para> - <para> - If a driver advertises render node support, DRM core will create a - separate render node called renderD&lt;num&gt;. There will - be one render node per device. No ioctls except PRIME-related ioctls - will be allowed on this node. Especially GEM_OPEN will be - explicitly prohibited. Render nodes are designed to avoid the - buffer-leaks, which occur if clients guess the flink names or mmap - offsets on the legacy interface. Additionally to this basic interface, - drivers must mark their driver-dependent render-only ioctls as - DRM_RENDER_ALLOW so render clients can use them. Driver - authors must be careful not to allow any privileged ioctls on render - nodes. - </para> - <para> - With render nodes, user-space can now control access to the render node - via basic file-system access-modes. A running graphics server which - authenticates clients on the privileged primary/legacy node is no longer - required. Instead, a client can open the render node and is immediately - granted GPU access. Communication between clients (or servers) is done - via PRIME. FLINK from render node to legacy node is not supported. New - clients must not use the insecure FLINK interface. - </para> - <para> - Besides dropping all modeset/global ioctls, render nodes also drop the - DRM-Master concept. There is no reason to associate render clients with - a DRM-Master as they are independent of any graphics server. Besides, - they must work without any running master, anyway. - Drivers must be able to run without a master object if they support - render nodes. If, on the other hand, a driver requires shared state - between clients which is visible to user-space and accessible beyond - open-file boundaries, they cannot support render nodes. - </para> - </sect1> - - <!-- External: vblank handling --> - - <sect1> - <title>VBlank event handling</title> - <para> - The DRM core exposes two vertical blank related ioctls: - <variablelist> - <varlistentry> - <term>DRM_IOCTL_WAIT_VBLANK</term> - <listitem> - <para> - This takes a struct drm_wait_vblank structure as its argument, - and it is used to block or request a signal when a specified - vblank event occurs. - </para> - </listitem> - </varlistentry> - <varlistentry> - <term>DRM_IOCTL_MODESET_CTL</term> - <listitem> - <para> - This was only used for user-mode-settind drivers around - modesetting changes to allow the kernel to update the vblank - interrupt after mode setting, since on many devices the vertical - blank counter is reset to 0 at some point during modeset. Modern - drivers should not call this any more since with kernel mode - setting it is a no-op. - </para> - </listitem> - </varlistentry> - </variablelist> - </para> - </sect1> - - </chapter> -</part> -<part id="drmDrivers"> - <title>DRM Drivers</title> - - <partintro> - <para> - This second part of the DRM Developer's Guide documents driver code, - implementation details and also all the driver-specific userspace - interfaces. Especially since all hardware-acceleration interfaces to - userspace are driver specific for efficiency and other reasons these - interfaces can be rather substantial. Hence every driver has its own - chapter. - </para> - </partintro> - - <chapter id="drmI915"> - <title>drm/i915 Intel GFX Driver</title> - <para> - The drm/i915 driver supports all (with the exception of some very early - models) integrated GFX chipsets with both Intel display and rendering - blocks. This excludes a set of SoC platforms with an SGX rendering unit, - those have basic support through the gma500 drm driver. - </para> - <sect1> - <title>Core Driver Infrastructure</title> - <para> - This section covers core driver infrastructure used by both the display - and the GEM parts of the driver. - </para> - <sect2> - <title>Runtime Power Management</title> -!Pdrivers/gpu/drm/i915/intel_runtime_pm.c runtime pm -!Idrivers/gpu/drm/i915/intel_runtime_pm.c -!Idrivers/gpu/drm/i915/intel_uncore.c - </sect2> - <sect2> - <title>Interrupt Handling</title> -!Pdrivers/gpu/drm/i915/i915_irq.c interrupt handling -!Fdrivers/gpu/drm/i915/i915_irq.c intel_irq_init intel_irq_init_hw intel_hpd_init -!Fdrivers/gpu/drm/i915/i915_irq.c intel_runtime_pm_disable_interrupts -!Fdrivers/gpu/drm/i915/i915_irq.c intel_runtime_pm_enable_interrupts - </sect2> - <sect2> - <title>Intel GVT-g Guest Support(vGPU)</title> -!Pdrivers/gpu/drm/i915/i915_vgpu.c Intel GVT-g guest support -!Idrivers/gpu/drm/i915/i915_vgpu.c - </sect2> - </sect1> - <sect1> - <title>Display Hardware Handling</title> - <para> - This section covers everything related to the display hardware including - the mode setting infrastructure, plane, sprite and cursor handling and - display, output probing and related topics. - </para> - <sect2> - <title>Mode Setting Infrastructure</title> - <para> - The i915 driver is thus far the only DRM driver which doesn't use the - common DRM helper code to implement mode setting sequences. Thus it - has its own tailor-made infrastructure for executing a display - configuration change. - </para> - </sect2> - <sect2> - <title>Frontbuffer Tracking</title> -!Pdrivers/gpu/drm/i915/intel_frontbuffer.c frontbuffer tracking -!Idrivers/gpu/drm/i915/intel_frontbuffer.c -!Fdrivers/gpu/drm/i915/i915_gem.c i915_gem_track_fb - </sect2> - <sect2> - <title>Display FIFO Underrun Reporting</title> -!Pdrivers/gpu/drm/i915/intel_fifo_underrun.c fifo underrun handling -!Idrivers/gpu/drm/i915/intel_fifo_underrun.c - </sect2> - <sect2> - <title>Plane Configuration</title> - <para> - This section covers plane configuration and composition with the - primary plane, sprites, cursors and overlays. This includes the - infrastructure to do atomic vsync'ed updates of all this state and - also tightly coupled topics like watermark setup and computation, - framebuffer compression and panel self refresh. - </para> - </sect2> - <sect2> - <title>Atomic Plane Helpers</title> -!Pdrivers/gpu/drm/i915/intel_atomic_plane.c atomic plane helpers -!Idrivers/gpu/drm/i915/intel_atomic_plane.c - </sect2> - <sect2> - <title>Output Probing</title> - <para> - This section covers output probing and related infrastructure like the - hotplug interrupt storm detection and mitigation code. Note that the - i915 driver still uses most of the common DRM helper code for output - probing, so those sections fully apply. - </para> - </sect2> - <sect2> - <title>Hotplug</title> -!Pdrivers/gpu/drm/i915/intel_hotplug.c Hotplug -!Idrivers/gpu/drm/i915/intel_hotplug.c - </sect2> - <sect2> - <title>High Definition Audio</title> -!Pdrivers/gpu/drm/i915/intel_audio.c High Definition Audio over HDMI and Display Port -!Idrivers/gpu/drm/i915/intel_audio.c - </sect2> - <sect2> - <title>Panel Self Refresh PSR (PSR/SRD)</title> -!Pdrivers/gpu/drm/i915/intel_psr.c Panel Self Refresh (PSR/SRD) -!Idrivers/gpu/drm/i915/intel_psr.c - </sect2> - <sect2> - <title>Frame Buffer Compression (FBC)</title> -!Pdrivers/gpu/drm/i915/intel_fbc.c Frame Buffer Compression (FBC) -!Idrivers/gpu/drm/i915/intel_fbc.c - </sect2> - <sect2> - <title>Display Refresh Rate Switching (DRRS)</title> -!Pdrivers/gpu/drm/i915/intel_dp.c Display Refresh Rate Switching (DRRS) -!Fdrivers/gpu/drm/i915/intel_dp.c intel_dp_set_drrs_state -!Fdrivers/gpu/drm/i915/intel_dp.c intel_edp_drrs_enable -!Fdrivers/gpu/drm/i915/intel_dp.c intel_edp_drrs_disable -!Fdrivers/gpu/drm/i915/intel_dp.c intel_edp_drrs_invalidate -!Fdrivers/gpu/drm/i915/intel_dp.c intel_edp_drrs_flush -!Fdrivers/gpu/drm/i915/intel_dp.c intel_dp_drrs_init - - </sect2> - <sect2> - <title>DPIO</title> -!Pdrivers/gpu/drm/i915/i915_reg.h DPIO - </sect2> - - <sect2> - <title>CSR firmware support for DMC</title> -!Pdrivers/gpu/drm/i915/intel_csr.c csr support for dmc -!Idrivers/gpu/drm/i915/intel_csr.c - </sect2> - </sect1> - - <sect1> - <title>Memory Management and Command Submission</title> - <para> - This sections covers all things related to the GEM implementation in the - i915 driver. - </para> - <sect2> - <title>Batchbuffer Parsing</title> -!Pdrivers/gpu/drm/i915/i915_cmd_parser.c batch buffer command parser -!Idrivers/gpu/drm/i915/i915_cmd_parser.c - </sect2> - <sect2> - <title>Batchbuffer Pools</title> -!Pdrivers/gpu/drm/i915/i915_gem_batch_pool.c batch pool -!Idrivers/gpu/drm/i915/i915_gem_batch_pool.c - </sect2> - <sect2> - <title>Logical Rings, Logical Ring Contexts and Execlists</title> -!Pdrivers/gpu/drm/i915/intel_lrc.c Logical Rings, Logical Ring Contexts and Execlists -!Idrivers/gpu/drm/i915/intel_lrc.c - </sect2> - <sect2> - <title>Global GTT views</title> -!Pdrivers/gpu/drm/i915/i915_gem_gtt.c Global GTT views -!Idrivers/gpu/drm/i915/i915_gem_gtt.c - </sect2> - <sect2> - <title>GTT Fences and Swizzling</title> -!Idrivers/gpu/drm/i915/i915_gem_fence.c - <sect3> - <title>Global GTT Fence Handling</title> -!Pdrivers/gpu/drm/i915/i915_gem_fence.c fence register handling - </sect3> - <sect3> - <title>Hardware Tiling and Swizzling Details</title> -!Pdrivers/gpu/drm/i915/i915_gem_fence.c tiling swizzling details - </sect3> - </sect2> - <sect2> - <title>Object Tiling IOCTLs</title> -!Idrivers/gpu/drm/i915/i915_gem_tiling.c -!Pdrivers/gpu/drm/i915/i915_gem_tiling.c buffer object tiling - </sect2> - <sect2> - <title>Buffer Object Eviction</title> - <para> - This section documents the interface functions for evicting buffer - objects to make space available in the virtual gpu address spaces. - Note that this is mostly orthogonal to shrinking buffer objects - caches, which has the goal to make main memory (shared with the gpu - through the unified memory architecture) available. - </para> -!Idrivers/gpu/drm/i915/i915_gem_evict.c - </sect2> - <sect2> - <title>Buffer Object Memory Shrinking</title> - <para> - This section documents the interface function for shrinking memory - usage of buffer object caches. Shrinking is used to make main memory - available. Note that this is mostly orthogonal to evicting buffer - objects, which has the goal to make space in gpu virtual address - spaces. - </para> -!Idrivers/gpu/drm/i915/i915_gem_shrinker.c - </sect2> - </sect1> - <sect1> - <title>GuC-based Command Submission</title> - <sect2> - <title>GuC</title> -!Pdrivers/gpu/drm/i915/intel_guc_loader.c GuC-specific firmware loader -!Idrivers/gpu/drm/i915/intel_guc_loader.c - </sect2> - <sect2> - <title>GuC Client</title> -!Pdrivers/gpu/drm/i915/i915_guc_submission.c GuC-based command submissison -!Idrivers/gpu/drm/i915/i915_guc_submission.c - </sect2> - </sect1> - - <sect1> - <title> Tracing </title> - <para> - This sections covers all things related to the tracepoints implemented in - the i915 driver. - </para> - <sect2> - <title> i915_ppgtt_create and i915_ppgtt_release </title> -!Pdrivers/gpu/drm/i915/i915_trace.h i915_ppgtt_create and i915_ppgtt_release tracepoints - </sect2> - <sect2> - <title> i915_context_create and i915_context_free </title> -!Pdrivers/gpu/drm/i915/i915_trace.h i915_context_create and i915_context_free tracepoints - </sect2> - <sect2> - <title> switch_mm </title> -!Pdrivers/gpu/drm/i915/i915_trace.h switch_mm tracepoint - </sect2> - </sect1> - - </chapter> -!Cdrivers/gpu/drm/i915/i915_irq.c -</part> -</book> diff --git a/Documentation/DocBook/gpu.tmpl b/Documentation/DocBook/gpu.tmpl new file mode 100644 index 0000000..94c600c --- /dev/null +++ b/Documentation/DocBook/gpu.tmpl @@ -0,0 +1,4189 @@ +<?xml version="1.0" encoding="UTF-8"?> +<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" + "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []> + +<book id="drmDevelopersGuide"> + <bookinfo> + <title>Linux GPU Driver Developer's Guide</title> + + <authorgroup> + <author> + <firstname>Jesse</firstname> + <surname>Barnes</surname> + <contrib>Initial version</contrib> + <affiliation> + <orgname>Intel Corporation</orgname> + <address> + <email>jesse.barnes@intel.com</email> + </address> + </affiliation> + </author> + <author> + <firstname>Laurent</firstname> + <surname>Pinchart</surname> + <contrib>Driver internals</contrib> + <affiliation> + <orgname>Ideas on board SPRL</orgname> + <address> + <email>laurent.pinchart@ideasonboard.com</email> + </address> + </affiliation> + </author> + <author> + <firstname>Daniel</firstname> + <surname>Vetter</surname> + <contrib>Contributions all over the place</contrib> + <affiliation> + <orgname>Intel Corporation</orgname> + <address> + <email>daniel.vetter@ffwll.ch</email> + </address> + </affiliation> + </author> + </authorgroup> + + <copyright> + <year>2008-2009</year> + <year>2013-2014</year> + <holder>Intel Corporation</holder> + </copyright> + <copyright> + <year>2012</year> + <holder>Laurent Pinchart</holder> + </copyright> + + <legalnotice> + <para> + The contents of this file may be used under the terms of the GNU + General Public License version 2 (the "GPL") as distributed in + the kernel source COPYING file. + </para> + </legalnotice> + + <revhistory> + <!-- Put document revisions here, newest first. --> + <revision> + <revnumber>1.0</revnumber> + <date>2012-07-13</date> + <authorinitials>LP</authorinitials> + <revremark>Added extensive documentation about driver internals. + </revremark> + </revision> + </revhistory> + </bookinfo> + +<toc></toc> + +<part id="drmCore"> + <title>DRM Core</title> + <partintro> + <para> + This first part of the DRM Developer's Guide documents core DRM code, + helper libraries for writing drivers and generic userspace interfaces + exposed by DRM drivers. + </para> + </partintro> + + <chapter id="drmIntroduction"> + <title>Introduction</title> + <para> + The Linux DRM layer contains code intended to support the needs + of complex graphics devices, usually containing programmable + pipelines well suited to 3D graphics acceleration. Graphics + drivers in the kernel may make use of DRM functions to make + tasks like memory management, interrupt handling and DMA easier, + and provide a uniform interface to applications. + </para> + <para> + A note on versions: this guide covers features found in the DRM + tree, including the TTM memory manager, output configuration and + mode setting, and the new vblank internals, in addition to all + the regular features found in current kernels. + </para> + <para> + [Insert diagram of typical DRM stack here] + </para> + </chapter> + + <!-- Internals --> + + <chapter id="drmInternals"> + <title>DRM Internals</title> + <para> + This chapter documents DRM internals relevant to driver authors + and developers working to add support for the latest features to + existing drivers. + </para> + <para> + First, we go over some typical driver initialization + requirements, like setting up command buffers, creating an + initial output configuration, and initializing core services. + Subsequent sections cover core internals in more detail, + providing implementation notes and examples. + </para> + <para> + The DRM layer provides several services to graphics drivers, + many of them driven by the application interfaces it provides + through libdrm, the library that wraps most of the DRM ioctls. + These include vblank event handling, memory + management, output management, framebuffer management, command + submission &amp; fencing, suspend/resume support, and DMA + services. + </para> + + <!-- Internals: driver init --> + + <sect1> + <title>Driver Initialization</title> + <para> + At the core of every DRM driver is a <structname>drm_driver</structname> + structure. Drivers typically statically initialize a drm_driver structure, + and then pass it to one of the <function>drm_*_init()</function> functions + to register it with the DRM subsystem. + </para> + <para> + Newer drivers that no longer require a <structname>drm_bus</structname> + structure can alternatively use the low-level device initialization and + registration functions such as <function>drm_dev_alloc()</function> and + <function>drm_dev_register()</function> directly. + </para> + <para> + The <structname>drm_driver</structname> structure contains static + information that describes the driver and features it supports, and + pointers to methods that the DRM core will call to implement the DRM API. + We will first go through the <structname>drm_driver</structname> static + information fields, and will then describe individual operations in + details as they get used in later sections. + </para> + <sect2> + <title>Driver Information</title> + <sect3> + <title>Driver Features</title> + <para> + Drivers inform the DRM core about their requirements and supported + features by setting appropriate flags in the + <structfield>driver_features</structfield> field. Since those flags + influence the DRM core behaviour since registration time, most of them + must be set to registering the <structname>drm_driver</structname> + instance. + </para> + <synopsis>u32 driver_features;</synopsis> + <variablelist> + <title>Driver Feature Flags</title> + <varlistentry> + <term>DRIVER_USE_AGP</term> + <listitem><para> + Driver uses AGP interface, the DRM core will manage AGP resources. + </para></listitem> + </varlistentry> + <varlistentry> + <term>DRIVER_REQUIRE_AGP</term> + <listitem><para> + Driver needs AGP interface to function. AGP initialization failure + will become a fatal error. + </para></listitem> + </varlistentry> + <varlistentry> + <term>DRIVER_PCI_DMA</term> + <listitem><para> + Driver is capable of PCI DMA, mapping of PCI DMA buffers to + userspace will be enabled. Deprecated. + </para></listitem> + </varlistentry> + <varlistentry> + <term>DRIVER_SG</term> + <listitem><para> + Driver can perform scatter/gather DMA, allocation and mapping of + scatter/gather buffers will be enabled. Deprecated. + </para></listitem> + </varlistentry> + <varlistentry> + <term>DRIVER_HAVE_DMA</term> + <listitem><para> + Driver supports DMA, the userspace DMA API will be supported. + Deprecated. + </para></listitem> + </varlistentry> + <varlistentry> + <term>DRIVER_HAVE_IRQ</term><term>DRIVER_IRQ_SHARED</term> + <listitem><para> + DRIVER_HAVE_IRQ indicates whether the driver has an IRQ handler + managed by the DRM Core. The core will support simple IRQ handler + installation when the flag is set. The installation process is + described in <xref linkend="drm-irq-registration"/>.</para> + <para>DRIVER_IRQ_SHARED indicates whether the device &amp; handler + support shared IRQs (note that this is required of PCI drivers). + </para></listitem> + </varlistentry> + <varlistentry> + <term>DRIVER_GEM</term> + <listitem><para> + Driver use the GEM memory manager. + </para></listitem> + </varlistentry> + <varlistentry> + <term>DRIVER_MODESET</term> + <listitem><para> + Driver supports mode setting interfaces (KMS). + </para></listitem> + </varlistentry> + <varlistentry> + <term>DRIVER_PRIME</term> + <listitem><para> + Driver implements DRM PRIME buffer sharing. + </para></listitem> + </varlistentry> + <varlistentry> + <term>DRIVER_RENDER</term> + <listitem><para> + Driver supports dedicated render nodes. + </para></listitem> + </varlistentry> + <varlistentry> + <term>DRIVER_ATOMIC</term> + <listitem><para> + Driver supports atomic properties. In this case the driver + must implement appropriate obj->atomic_get_property() vfuncs + for any modeset objects with driver specific properties. + </para></listitem> + </varlistentry> + </variablelist> + </sect3> + <sect3> + <title>Major, Minor and Patchlevel</title> + <synopsis>int major; +int minor; +int patchlevel;</synopsis> + <para> + The DRM core identifies driver versions by a major, minor and patch + level triplet. The information is printed to the kernel log at + initialization time and passed to userspace through the + DRM_IOCTL_VERSION ioctl. + </para> + <para> + The major and minor numbers are also used to verify the requested driver + API version passed to DRM_IOCTL_SET_VERSION. When the driver API changes + between minor versions, applications can call DRM_IOCTL_SET_VERSION to + select a specific version of the API. If the requested major isn't equal + to the driver major, or the requested minor is larger than the driver + minor, the DRM_IOCTL_SET_VERSION call will return an error. Otherwise + the driver's set_version() method will be called with the requested + version. + </para> + </sect3> + <sect3> + <title>Name, Description and Date</title> + <synopsis>char *name; +char *desc; +char *date;</synopsis> + <para> + The driver name is printed to the kernel log at initialization time, + used for IRQ registration and passed to userspace through + DRM_IOCTL_VERSION. + </para> + <para> + The driver description is a purely informative string passed to + userspace through the DRM_IOCTL_VERSION ioctl and otherwise unused by + the kernel. + </para> + <para> + The driver date, formatted as YYYYMMDD, is meant to identify the date of + the latest modification to the driver. However, as most drivers fail to + update it, its value is mostly useless. The DRM core prints it to the + kernel log at initialization time and passes it to userspace through the + DRM_IOCTL_VERSION ioctl. + </para> + </sect3> + </sect2> + <sect2> + <title>Device Registration</title> + <para> + A number of functions are provided to help with device registration. + The functions deal with PCI and platform devices, respectively. + </para> +!Edrivers/gpu/drm/drm_pci.c +!Edrivers/gpu/drm/drm_platform.c + <para> + New drivers that no longer rely on the services provided by the + <structname>drm_bus</structname> structure can call the low-level + device registration functions directly. The + <function>drm_dev_alloc()</function> function can be used to allocate + and initialize a new <structname>drm_device</structname> structure. + Drivers will typically want to perform some additional setup on this + structure, such as allocating driver-specific data and storing a + pointer to it in the DRM device's <structfield>dev_private</structfield> + field. Drivers should also set the device's unique name using the + <function>drm_dev_set_unique()</function> function. After it has been + set up a device can be registered with the DRM subsystem by calling + <function>drm_dev_register()</function>. This will cause the device to + be exposed to userspace and will call the driver's + <structfield>.load()</structfield> implementation. When a device is + removed, the DRM device can safely be unregistered and freed by calling + <function>drm_dev_unregister()</function> followed by a call to + <function>drm_dev_unref()</function>. + </para> +!Edrivers/gpu/drm/drm_drv.c + </sect2> + <sect2> + <title>Driver Load</title> + <para> + The <methodname>load</methodname> method is the driver and device + initialization entry point. The method is responsible for allocating and + initializing driver private data, performing resource allocation and + mapping (e.g. acquiring + clocks, mapping registers or allocating command buffers), initializing + the memory manager (<xref linkend="drm-memory-management"/>), installing + the IRQ handler (<xref linkend="drm-irq-registration"/>), setting up + vertical blanking handling (<xref linkend="drm-vertical-blank"/>), mode + setting (<xref linkend="drm-mode-setting"/>) and initial output + configuration (<xref linkend="drm-kms-init"/>). + </para> + <note><para> + If compatibility is a concern (e.g. with drivers converted over from + User Mode Setting to Kernel Mode Setting), care must be taken to prevent + device initialization and control that is incompatible with currently + active userspace drivers. For instance, if user level mode setting + drivers are in use, it would be problematic to perform output discovery + &amp; configuration at load time. Likewise, if user-level drivers + unaware of memory management are in use, memory management and command + buffer setup may need to be omitted. These requirements are + driver-specific, and care needs to be taken to keep both old and new + applications and libraries working. + </para></note> + <synopsis>int (*load) (struct drm_device *, unsigned long flags);</synopsis> + <para> + The method takes two arguments, a pointer to the newly created + <structname>drm_device</structname> and flags. The flags are used to + pass the <structfield>driver_data</structfield> field of the device id + corresponding to the device passed to <function>drm_*_init()</function>. + Only PCI devices currently use this, USB and platform DRM drivers have + their <methodname>load</methodname> method called with flags to 0. + </para> + <sect3> + <title>Driver Private Data</title> + <para> + The driver private hangs off the main + <structname>drm_device</structname> structure and can be used for + tracking various device-specific bits of information, like register + offsets, command buffer status, register state for suspend/resume, etc. + At load time, a driver may simply allocate one and set + <structname>drm_device</structname>.<structfield>dev_priv</structfield> + appropriately; it should be freed and + <structname>drm_device</structname>.<structfield>dev_priv</structfield> + set to NULL when the driver is unloaded. + </para> + </sect3> + <sect3 id="drm-irq-registration"> + <title>IRQ Registration</title> + <para> + The DRM core tries to facilitate IRQ handler registration and + unregistration by providing <function>drm_irq_install</function> and + <function>drm_irq_uninstall</function> functions. Those functions only + support a single interrupt per device, devices that use more than one + IRQs need to be handled manually. + </para> + <sect4> + <title>Managed IRQ Registration</title> + <para> + <function>drm_irq_install</function> starts by calling the + <methodname>irq_preinstall</methodname> driver operation. The operation + is optional and must make sure that the interrupt will not get fired by + clearing all pending interrupt flags or disabling the interrupt. + </para> + <para> + The passed-in IRQ will then be requested by a call to + <function>request_irq</function>. If the DRIVER_IRQ_SHARED driver + feature flag is set, a shared (IRQF_SHARED) IRQ handler will be + requested. + </para> + <para> + The IRQ handler function must be provided as the mandatory irq_handler + driver operation. It will get passed directly to + <function>request_irq</function> and thus has the same prototype as all + IRQ handlers. It will get called with a pointer to the DRM device as the + second argument. + </para> + <para> + Finally the function calls the optional + <methodname>irq_postinstall</methodname> driver operation. The operation + usually enables interrupts (excluding the vblank interrupt, which is + enabled separately), but drivers may choose to enable/disable interrupts + at a different time. + </para> + <para> + <function>drm_irq_uninstall</function> is similarly used to uninstall an + IRQ handler. It starts by waking up all processes waiting on a vblank + interrupt to make sure they don't hang, and then calls the optional + <methodname>irq_uninstall</methodname> driver operation. The operation + must disable all hardware interrupts. Finally the function frees the IRQ + by calling <function>free_irq</function>. + </para> + </sect4> + <sect4> + <title>Manual IRQ Registration</title> + <para> + Drivers that require multiple interrupt handlers can't use the managed + IRQ registration functions. In that case IRQs must be registered and + unregistered manually (usually with the <function>request_irq</function> + and <function>free_irq</function> functions, or their devm_* equivalent). + </para> + <para> + When manually registering IRQs, drivers must not set the DRIVER_HAVE_IRQ + driver feature flag, and must not provide the + <methodname>irq_handler</methodname> driver operation. They must set the + <structname>drm_device</structname> <structfield>irq_enabled</structfield> + field to 1 upon registration of the IRQs, and clear it to 0 after + unregistering the IRQs. + </para> + </sect4> + </sect3> + <sect3> + <title>Memory Manager Initialization</title> + <para> + Every DRM driver requires a memory manager which must be initialized at + load time. DRM currently contains two memory managers, the Translation + Table Manager (TTM) and the Graphics Execution Manager (GEM). + This document describes the use of the GEM memory manager only. See + <xref linkend="drm-memory-management"/> for details. + </para> + </sect3> + <sect3> + <title>Miscellaneous Device Configuration</title> + <para> + Another task that may be necessary for PCI devices during configuration + is mapping the video BIOS. On many devices, the VBIOS describes device + configuration, LCD panel timings (if any), and contains flags indicating + device state. Mapping the BIOS can be done using the pci_map_rom() call, + a convenience function that takes care of mapping the actual ROM, + whether it has been shadowed into memory (typically at address 0xc0000) + or exists on the PCI device in the ROM BAR. Note that after the ROM has + been mapped and any necessary information has been extracted, it should + be unmapped; on many devices, the ROM address decoder is shared with + other BARs, so leaving it mapped could cause undesired behaviour like + hangs or memory corruption. + <!--!Fdrivers/pci/rom.c pci_map_rom--> + </para> + </sect3> + </sect2> + </sect1> + + <!-- Internals: memory management --> + + <sect1 id="drm-memory-management"> + <title>Memory management</title> + <para> + Modern Linux systems require large amount of graphics memory to store + frame buffers, textures, vertices and other graphics-related data. Given + the very dynamic nature of many of that data, managing graphics memory + efficiently is thus crucial for the graphics stack and plays a central + role in the DRM infrastructure. + </para> + <para> + The DRM core includes two memory managers, namely Translation Table Maps + (TTM) and Graphics Execution Manager (GEM). TTM was the first DRM memory + manager to be developed and tried to be a one-size-fits-them all + solution. It provides a single userspace API to accommodate the need of + all hardware, supporting both Unified Memory Architecture (UMA) devices + and devices with dedicated video RAM (i.e. most discrete video cards). + This resulted in a large, complex piece of code that turned out to be + hard to use for driver development. + </para> + <para> + GEM started as an Intel-sponsored project in reaction to TTM's + complexity. Its design philosophy is completely different: instead of + providing a solution to every graphics memory-related problems, GEM + identified common code between drivers and created a support library to + share it. GEM has simpler initialization and execution requirements than + TTM, but has no video RAM management capabilities and is thus limited to + UMA devices. + </para> + <sect2> + <title>The Translation Table Manager (TTM)</title> + <para> + TTM design background and information belongs here. + </para> + <sect3> + <title>TTM initialization</title> + <warning><para>This section is outdated.</para></warning> + <para> + Drivers wishing to support TTM must fill out a drm_bo_driver + structure. The structure contains several fields with function + pointers for initializing the TTM, allocating and freeing memory, + waiting for command completion and fence synchronization, and memory + migration. See the radeon_ttm.c file for an example of usage. + </para> + <para> + The ttm_global_reference structure is made up of several fields: + </para> + <programlisting> + struct ttm_global_reference { + enum ttm_global_types global_type; + size_t size; + void *object; + int (*init) (struct ttm_global_reference *); + void (*release) (struct ttm_global_reference *); + }; + </programlisting> + <para> + There should be one global reference structure for your memory + manager as a whole, and there will be others for each object + created by the memory manager at runtime. Your global TTM should + have a type of TTM_GLOBAL_TTM_MEM. The size field for the global + object should be sizeof(struct ttm_mem_global), and the init and + release hooks should point at your driver-specific init and + release routines, which probably eventually call + ttm_mem_global_init and ttm_mem_global_release, respectively. + </para> + <para> + Once your global TTM accounting structure is set up and initialized + by calling ttm_global_item_ref() on it, + you need to create a buffer object TTM to + provide a pool for buffer object allocation by clients and the + kernel itself. The type of this object should be TTM_GLOBAL_TTM_BO, + and its size should be sizeof(struct ttm_bo_global). Again, + driver-specific init and release functions may be provided, + likely eventually calling ttm_bo_global_init() and + ttm_bo_global_release(), respectively. Also, like the previous + object, ttm_global_item_ref() is used to create an initial reference + count for the TTM, which will call your initialization function. + </para> + </sect3> + </sect2> + <sect2 id="drm-gem"> + <title>The Graphics Execution Manager (GEM)</title> + <para> + The GEM design approach has resulted in a memory manager that doesn't + provide full coverage of all (or even all common) use cases in its + userspace or kernel API. GEM exposes a set of standard memory-related + operations to userspace and a set of helper functions to drivers, and let + drivers implement hardware-specific operations with their own private API. + </para> + <para> + The GEM userspace API is described in the + <ulink url="http://lwn.net/Articles/283798/"><citetitle>GEM - the Graphics + Execution Manager</citetitle></ulink> article on LWN. While slightly + outdated, the document provides a good overview of the GEM API principles. + Buffer allocation and read and write operations, described as part of the + common GEM API, are currently implemented using driver-specific ioctls. + </para> + <para> + GEM is data-agnostic. It manages abstract buffer objects without knowing + what individual buffers contain. APIs that require knowledge of buffer + contents or purpose, such as buffer allocation or synchronization + primitives, are thus outside of the scope of GEM and must be implemented + using driver-specific ioctls. + </para> + <para> + On a fundamental level, GEM involves several operations: + <itemizedlist> + <listitem>Memory allocation and freeing</listitem> + <listitem>Command execution</listitem> + <listitem>Aperture management at command execution time</listitem> + </itemizedlist> + Buffer object allocation is relatively straightforward and largely + provided by Linux's shmem layer, which provides memory to back each + object. + </para> + <para> + Device-specific operations, such as command execution, pinning, buffer + read &amp; write, mapping, and domain ownership transfers are left to + driver-specific ioctls. + </para> + <sect3> + <title>GEM Initialization</title> + <para> + Drivers that use GEM must set the DRIVER_GEM bit in the struct + <structname>drm_driver</structname> + <structfield>driver_features</structfield> field. The DRM core will + then automatically initialize the GEM core before calling the + <methodname>load</methodname> operation. Behind the scene, this will + create a DRM Memory Manager object which provides an address space + pool for object allocation. + </para> + <para> + In a KMS configuration, drivers need to allocate and initialize a + command ring buffer following core GEM initialization if required by + the hardware. UMA devices usually have what is called a "stolen" + memory region, which provides space for the initial framebuffer and + large, contiguous memory regions required by the device. This space is + typically not managed by GEM, and must be initialized separately into + its own DRM MM object. + </para> + </sect3> + <sect3> + <title>GEM Objects Creation</title> + <para> + GEM splits creation of GEM objects and allocation of the memory that + backs them in two distinct operations. + </para> + <para> + GEM objects are represented by an instance of struct + <structname>drm_gem_object</structname>. Drivers usually need to extend + GEM objects with private information and thus create a driver-specific + GEM object structure type that embeds an instance of struct + <structname>drm_gem_object</structname>. + </para> + <para> + To create a GEM object, a driver allocates memory for an instance of its + specific GEM object type and initializes the embedded struct + <structname>drm_gem_object</structname> with a call to + <function>drm_gem_object_init</function>. The function takes a pointer to + the DRM device, a pointer to the GEM object and the buffer object size + in bytes. + </para> + <para> + GEM uses shmem to allocate anonymous pageable memory. + <function>drm_gem_object_init</function> will create an shmfs file of + the requested size and store it into the struct + <structname>drm_gem_object</structname> <structfield>filp</structfield> + field. The memory is used as either main storage for the object when the + graphics hardware uses system memory directly or as a backing store + otherwise. + </para> + <para> + Drivers are responsible for the actual physical pages allocation by + calling <function>shmem_read_mapping_page_gfp</function> for each page. + Note that they can decide to allocate pages when initializing the GEM + object, or to delay allocation until the memory is needed (for instance + when a page fault occurs as a result of a userspace memory access or + when the driver needs to start a DMA transfer involving the memory). + </para> + <para> + Anonymous pageable memory allocation is not always desired, for instance + when the hardware requires physically contiguous system memory as is + often the case in embedded devices. Drivers can create GEM objects with + no shmfs backing (called private GEM objects) by initializing them with + a call to <function>drm_gem_private_object_init</function> instead of + <function>drm_gem_object_init</function>. Storage for private GEM + objects must be managed by drivers. + </para> + <para> + Drivers that do not need to extend GEM objects with private information + can call the <function>drm_gem_object_alloc</function> function to + allocate and initialize a struct <structname>drm_gem_object</structname> + instance. The GEM core will call the optional driver + <methodname>gem_init_object</methodname> operation after initializing + the GEM object with <function>drm_gem_object_init</function>. + <synopsis>int (*gem_init_object) (struct drm_gem_object *obj);</synopsis> + </para> + <para> + No alloc-and-init function exists for private GEM objects. + </para> + </sect3> + <sect3> + <title>GEM Objects Lifetime</title> + <para> + All GEM objects are reference-counted by the GEM core. References can be + acquired and release by <function>calling drm_gem_object_reference</function> + and <function>drm_gem_object_unreference</function> respectively. The + caller must hold the <structname>drm_device</structname> + <structfield>struct_mutex</structfield> lock. As a convenience, GEM + provides the <function>drm_gem_object_reference_unlocked</function> and + <function>drm_gem_object_unreference_unlocked</function> functions that + can be called without holding the lock. + </para> + <para> + When the last reference to a GEM object is released the GEM core calls + the <structname>drm_driver</structname> + <methodname>gem_free_object</methodname> operation. That operation is + mandatory for GEM-enabled drivers and must free the GEM object and all + associated resources. + </para> + <para> + <synopsis>void (*gem_free_object) (struct drm_gem_object *obj);</synopsis> + Drivers are responsible for freeing all GEM object resources, including + the resources created by the GEM core. If an mmap offset has been + created for the object (in which case + <structname>drm_gem_object</structname>::<structfield>map_list</structfield>::<structfield>map</structfield> + is not NULL) it must be freed by a call to + <function>drm_gem_free_mmap_offset</function>. The shmfs backing store + must be released by calling <function>drm_gem_object_release</function> + (that function can safely be called if no shmfs backing store has been + created). + </para> + </sect3> + <sect3> + <title>GEM Objects Naming</title> + <para> + Communication between userspace and the kernel refers to GEM objects + using local handles, global names or, more recently, file descriptors. + All of those are 32-bit integer values; the usual Linux kernel limits + apply to the file descriptors. + </para> + <para> + GEM handles are local to a DRM file. Applications get a handle to a GEM + object through a driver-specific ioctl, and can use that handle to refer + to the GEM object in other standard or driver-specific ioctls. Closing a + DRM file handle frees all its GEM handles and dereferences the + associated GEM objects. + </para> + <para> + To create a handle for a GEM object drivers call + <function>drm_gem_handle_create</function>. The function takes a pointer + to the DRM file and the GEM object and returns a locally unique handle. + When the handle is no longer needed drivers delete it with a call to + <function>drm_gem_handle_delete</function>. Finally the GEM object + associated with a handle can be retrieved by a call to + <function>drm_gem_object_lookup</function>. + </para> + <para> + Handles don't take ownership of GEM objects, they only take a reference + to the object that will be dropped when the handle is destroyed. To + avoid leaking GEM objects, drivers must make sure they drop the + reference(s) they own (such as the initial reference taken at object + creation time) as appropriate, without any special consideration for the + handle. For example, in the particular case of combined GEM object and + handle creation in the implementation of the + <methodname>dumb_create</methodname> operation, drivers must drop the + initial reference to the GEM object before returning the handle. + </para> + <para> + GEM names are similar in purpose to handles but are not local to DRM + files. They can be passed between processes to reference a GEM object + globally. Names can't be used directly to refer to objects in the DRM + API, applications must convert handles to names and names to handles + using the DRM_IOCTL_GEM_FLINK and DRM_IOCTL_GEM_OPEN ioctls + respectively. The conversion is handled by the DRM core without any + driver-specific support. + </para> + <para> + GEM also supports buffer sharing with dma-buf file descriptors through + PRIME. GEM-based drivers must use the provided helpers functions to + implement the exporting and importing correctly. See <xref linkend="drm-prime-support" />. + Since sharing file descriptors is inherently more secure than the + easily guessable and global GEM names it is the preferred buffer + sharing mechanism. Sharing buffers through GEM names is only supported + for legacy userspace. Furthermore PRIME also allows cross-device + buffer sharing since it is based on dma-bufs. + </para> + </sect3> + <sect3 id="drm-gem-objects-mapping"> + <title>GEM Objects Mapping</title> + <para> + Because mapping operations are fairly heavyweight GEM favours + read/write-like access to buffers, implemented through driver-specific + ioctls, over mapping buffers to userspace. However, when random access + to the buffer is needed (to perform software rendering for instance), + direct access to the object can be more efficient. + </para> + <para> + The mmap system call can't be used directly to map GEM objects, as they + don't have their own file handle. Two alternative methods currently + co-exist to map GEM objects to userspace. The first method uses a + driver-specific ioctl to perform the mapping operation, calling + <function>do_mmap</function> under the hood. This is often considered + dubious, seems to be discouraged for new GEM-enabled drivers, and will + thus not be described here. + </para> + <para> + The second method uses the mmap system call on the DRM file handle. + <synopsis>void *mmap(void *addr, size_t length, int prot, int flags, int fd, + off_t offset);</synopsis> + DRM identifies the GEM object to be mapped by a fake offset passed + through the mmap offset argument. Prior to being mapped, a GEM object + must thus be associated with a fake offset. To do so, drivers must call + <function>drm_gem_create_mmap_offset</function> on the object. The + function allocates a fake offset range from a pool and stores the + offset divided by PAGE_SIZE in + <literal>obj-&gt;map_list.hash.key</literal>. Care must be taken not to + call <function>drm_gem_create_mmap_offset</function> if a fake offset + has already been allocated for the object. This can be tested by + <literal>obj-&gt;map_list.map</literal> being non-NULL. + </para> + <para> + Once allocated, the fake offset value + (<literal>obj-&gt;map_list.hash.key &lt;&lt; PAGE_SHIFT</literal>) + must be passed to the application in a driver-specific way and can then + be used as the mmap offset argument. + </para> + <para> + The GEM core provides a helper method <function>drm_gem_mmap</function> + to handle object mapping. The method can be set directly as the mmap + file operation handler. It will look up the GEM object based on the + offset value and set the VMA operations to the + <structname>drm_driver</structname> <structfield>gem_vm_ops</structfield> + field. Note that <function>drm_gem_mmap</function> doesn't map memory to + userspace, but relies on the driver-provided fault handler to map pages + individually. + </para> + <para> + To use <function>drm_gem_mmap</function>, drivers must fill the struct + <structname>drm_driver</structname> <structfield>gem_vm_ops</structfield> + field with a pointer to VM operations. + </para> + <para> + <synopsis>struct vm_operations_struct *gem_vm_ops + + struct vm_operations_struct { + void (*open)(struct vm_area_struct * area); + void (*close)(struct vm_area_struct * area); + int (*fault)(struct vm_area_struct *vma, struct vm_fault *vmf); + };</synopsis> + </para> + <para> + The <methodname>open</methodname> and <methodname>close</methodname> + operations must update the GEM object reference count. Drivers can use + the <function>drm_gem_vm_open</function> and + <function>drm_gem_vm_close</function> helper functions directly as open + and close handlers. + </para> + <para> + The fault operation handler is responsible for mapping individual pages + to userspace when a page fault occurs. Depending on the memory + allocation scheme, drivers can allocate pages at fault time, or can + decide to allocate memory for the GEM object at the time the object is + created. + </para> + <para> + Drivers that want to map the GEM object upfront instead of handling page + faults can implement their own mmap file operation handler. + </para> + </sect3> + <sect3> + <title>Memory Coherency</title> + <para> + When mapped to the device or used in a command buffer, backing pages + for an object are flushed to memory and marked write combined so as to + be coherent with the GPU. Likewise, if the CPU accesses an object + after the GPU has finished rendering to the object, then the object + must be made coherent with the CPU's view of memory, usually involving + GPU cache flushing of various kinds. This core CPU&lt;-&gt;GPU + coherency management is provided by a device-specific ioctl, which + evaluates an object's current domain and performs any necessary + flushing or synchronization to put the object into the desired + coherency domain (note that the object may be busy, i.e. an active + render target; in that case, setting the domain blocks the client and + waits for rendering to complete before performing any necessary + flushing operations). + </para> + </sect3> + <sect3> + <title>Command Execution</title> + <para> + Perhaps the most important GEM function for GPU devices is providing a + command execution interface to clients. Client programs construct + command buffers containing references to previously allocated memory + objects, and then submit them to GEM. At that point, GEM takes care to + bind all the objects into the GTT, execute the buffer, and provide + necessary synchronization between clients accessing the same buffers. + This often involves evicting some objects from the GTT and re-binding + others (a fairly expensive operation), and providing relocation + support which hides fixed GTT offsets from clients. Clients must take + care not to submit command buffers that reference more objects than + can fit in the GTT; otherwise, GEM will reject them and no rendering + will occur. Similarly, if several objects in the buffer require fence + registers to be allocated for correct rendering (e.g. 2D blits on + pre-965 chips), care must be taken not to require more fence registers + than are available to the client. Such resource management should be + abstracted from the client in libdrm. + </para> + </sect3> + <sect3> + <title>GEM Function Reference</title> +!Edrivers/gpu/drm/drm_gem.c + </sect3> + </sect2> + <sect2> + <title>VMA Offset Manager</title> +!Pdrivers/gpu/drm/drm_vma_manager.c vma offset manager +!Edrivers/gpu/drm/drm_vma_manager.c +!Iinclude/drm/drm_vma_manager.h + </sect2> + <sect2 id="drm-prime-support"> + <title>PRIME Buffer Sharing</title> + <para> + PRIME is the cross device buffer sharing framework in drm, originally + created for the OPTIMUS range of multi-gpu platforms. To userspace + PRIME buffers are dma-buf based file descriptors. + </para> + <sect3> + <title>Overview and Driver Interface</title> + <para> + Similar to GEM global names, PRIME file descriptors are + also used to share buffer objects across processes. They offer + additional security: as file descriptors must be explicitly sent over + UNIX domain sockets to be shared between applications, they can't be + guessed like the globally unique GEM names. + </para> + <para> + Drivers that support the PRIME + API must set the DRIVER_PRIME bit in the struct + <structname>drm_driver</structname> + <structfield>driver_features</structfield> field, and implement the + <methodname>prime_handle_to_fd</methodname> and + <methodname>prime_fd_to_handle</methodname> operations. + </para> + <para> + <synopsis>int (*prime_handle_to_fd)(struct drm_device *dev, + struct drm_file *file_priv, uint32_t handle, + uint32_t flags, int *prime_fd); +int (*prime_fd_to_handle)(struct drm_device *dev, + struct drm_file *file_priv, int prime_fd, + uint32_t *handle);</synopsis> + Those two operations convert a handle to a PRIME file descriptor and + vice versa. Drivers must use the kernel dma-buf buffer sharing framework + to manage the PRIME file descriptors. Similar to the mode setting + API PRIME is agnostic to the underlying buffer object manager, as + long as handles are 32bit unsigned integers. + </para> + <para> + While non-GEM drivers must implement the operations themselves, GEM + drivers must use the <function>drm_gem_prime_handle_to_fd</function> + and <function>drm_gem_prime_fd_to_handle</function> helper functions. + Those helpers rely on the driver + <methodname>gem_prime_export</methodname> and + <methodname>gem_prime_import</methodname> operations to create a dma-buf + instance from a GEM object (dma-buf exporter role) and to create a GEM + object from a dma-buf instance (dma-buf importer role). + </para> + <para> + <synopsis>struct dma_buf * (*gem_prime_export)(struct drm_device *dev, + struct drm_gem_object *obj, + int flags); +struct drm_gem_object * (*gem_prime_import)(struct drm_device *dev, + struct dma_buf *dma_buf);</synopsis> + These two operations are mandatory for GEM drivers that support + PRIME. + </para> + </sect3> + <sect3> + <title>PRIME Helper Functions</title> +!Pdrivers/gpu/drm/drm_prime.c PRIME Helpers + </sect3> + </sect2> + <sect2> + <title>PRIME Function References</title> +!Edrivers/gpu/drm/drm_prime.c + </sect2> + <sect2> + <title>DRM MM Range Allocator</title> + <sect3> + <title>Overview</title> +!Pdrivers/gpu/drm/drm_mm.c Overview + </sect3> + <sect3> + <title>LRU Scan/Eviction Support</title> +!Pdrivers/gpu/drm/drm_mm.c lru scan roaster + </sect3> + </sect2> + <sect2> + <title>DRM MM Range Allocator Function References</title> +!Edrivers/gpu/drm/drm_mm.c +!Iinclude/drm/drm_mm.h + </sect2> + <sect2> + <title>CMA Helper Functions Reference</title> +!Pdrivers/gpu/drm/drm_gem_cma_helper.c cma helpers +!Edrivers/gpu/drm/drm_gem_cma_helper.c +!Iinclude/drm/drm_gem_cma_helper.h + </sect2> + </sect1> + + <!-- Internals: mode setting --> + + <sect1 id="drm-mode-setting"> + <title>Mode Setting</title> + <para> + Drivers must initialize the mode setting core by calling + <function>drm_mode_config_init</function> on the DRM device. The function + initializes the <structname>drm_device</structname> + <structfield>mode_config</structfield> field and never fails. Once done, + mode configuration must be setup by initializing the following fields. + </para> + <itemizedlist> + <listitem> + <synopsis>int min_width, min_height; +int max_width, max_height;</synopsis> + <para> + Minimum and maximum width and height of the frame buffers in pixel + units. + </para> + </listitem> + <listitem> + <synopsis>struct drm_mode_config_funcs *funcs;</synopsis> + <para>Mode setting functions.</para> + </listitem> + </itemizedlist> + <sect2> + <title>Display Modes Function Reference</title> +!Iinclude/drm/drm_modes.h +!Edrivers/gpu/drm/drm_modes.c + </sect2> + <sect2> + <title>Atomic Mode Setting Function Reference</title> +!Edrivers/gpu/drm/drm_atomic.c + </sect2> + <sect2> + <title>Frame Buffer Creation</title> + <synopsis>struct drm_framebuffer *(*fb_create)(struct drm_device *dev, + struct drm_file *file_priv, + struct drm_mode_fb_cmd2 *mode_cmd);</synopsis> + <para> + Frame buffers are abstract memory objects that provide a source of + pixels to scanout to a CRTC. Applications explicitly request the + creation of frame buffers through the DRM_IOCTL_MODE_ADDFB(2) ioctls and + receive an opaque handle that can be passed to the KMS CRTC control, + plane configuration and page flip functions. + </para> + <para> + Frame buffers rely on the underneath memory manager for low-level memory + operations. When creating a frame buffer applications pass a memory + handle (or a list of memory handles for multi-planar formats) through + the <parameter>drm_mode_fb_cmd2</parameter> argument. For drivers using + GEM as their userspace buffer management interface this would be a GEM + handle. Drivers are however free to use their own backing storage object + handles, e.g. vmwgfx directly exposes special TTM handles to userspace + and so expects TTM handles in the create ioctl and not GEM handles. + </para> + <para> + Drivers must first validate the requested frame buffer parameters passed + through the mode_cmd argument. In particular this is where invalid + sizes, pixel formats or pitches can be caught. + </para> + <para> + If the parameters are deemed valid, drivers then create, initialize and + return an instance of struct <structname>drm_framebuffer</structname>. + If desired the instance can be embedded in a larger driver-specific + structure. Drivers must fill its <structfield>width</structfield>, + <structfield>height</structfield>, <structfield>pitches</structfield>, + <structfield>offsets</structfield>, <structfield>depth</structfield>, + <structfield>bits_per_pixel</structfield> and + <structfield>pixel_format</structfield> fields from the values passed + through the <parameter>drm_mode_fb_cmd2</parameter> argument. They + should call the <function>drm_helper_mode_fill_fb_struct</function> + helper function to do so. + </para> + + <para> + The initialization of the new framebuffer instance is finalized with a + call to <function>drm_framebuffer_init</function> which takes a pointer + to DRM frame buffer operations (struct + <structname>drm_framebuffer_funcs</structname>). Note that this function + publishes the framebuffer and so from this point on it can be accessed + concurrently from other threads. Hence it must be the last step in the + driver's framebuffer initialization sequence. Frame buffer operations + are + <itemizedlist> + <listitem> + <synopsis>int (*create_handle)(struct drm_framebuffer *fb, + struct drm_file *file_priv, unsigned int *handle);</synopsis> + <para> + Create a handle to the frame buffer underlying memory object. If + the frame buffer uses a multi-plane format, the handle will + reference the memory object associated with the first plane. + </para> + <para> + Drivers call <function>drm_gem_handle_create</function> to create + the handle. + </para> + </listitem> + <listitem> + <synopsis>void (*destroy)(struct drm_framebuffer *framebuffer);</synopsis> + <para> + Destroy the frame buffer object and frees all associated + resources. Drivers must call + <function>drm_framebuffer_cleanup</function> to free resources + allocated by the DRM core for the frame buffer object, and must + make sure to unreference all memory objects associated with the + frame buffer. Handles created by the + <methodname>create_handle</methodname> operation are released by + the DRM core. + </para> + </listitem> + <listitem> + <synopsis>int (*dirty)(struct drm_framebuffer *framebuffer, + struct drm_file *file_priv, unsigned flags, unsigned color, + struct drm_clip_rect *clips, unsigned num_clips);</synopsis> + <para> + This optional operation notifies the driver that a region of the + frame buffer has changed in response to a DRM_IOCTL_MODE_DIRTYFB + ioctl call. + </para> + </listitem> + </itemizedlist> + </para> + <para> + The lifetime of a drm framebuffer is controlled with a reference count, + drivers can grab additional references with + <function>drm_framebuffer_reference</function>and drop them + again with <function>drm_framebuffer_unreference</function>. For + driver-private framebuffers for which the last reference is never + dropped (e.g. for the fbdev framebuffer when the struct + <structname>drm_framebuffer</structname> is embedded into the fbdev + helper struct) drivers can manually clean up a framebuffer at module + unload time with + <function>drm_framebuffer_unregister_private</function>. + </para> + </sect2> + <sect2> + <title>Dumb Buffer Objects</title> + <para> + The KMS API doesn't standardize backing storage object creation and + leaves it to driver-specific ioctls. Furthermore actually creating a + buffer object even for GEM-based drivers is done through a + driver-specific ioctl - GEM only has a common userspace interface for + sharing and destroying objects. While not an issue for full-fledged + graphics stacks that include device-specific userspace components (in + libdrm for instance), this limit makes DRM-based early boot graphics + unnecessarily complex. + </para> + <para> + Dumb objects partly alleviate the problem by providing a standard + API to create dumb buffers suitable for scanout, which can then be used + to create KMS frame buffers. + </para> + <para> + To support dumb objects drivers must implement the + <methodname>dumb_create</methodname>, + <methodname>dumb_destroy</methodname> and + <methodname>dumb_map_offset</methodname> operations. + </para> + <itemizedlist> + <listitem> + <synopsis>int (*dumb_create)(struct drm_file *file_priv, struct drm_device *dev, + struct drm_mode_create_dumb *args);</synopsis> + <para> + The <methodname>dumb_create</methodname> operation creates a driver + object (GEM or TTM handle) suitable for scanout based on the + width, height and depth from the struct + <structname>drm_mode_create_dumb</structname> argument. It fills the + argument's <structfield>handle</structfield>, + <structfield>pitch</structfield> and <structfield>size</structfield> + fields with a handle for the newly created object and its line + pitch and size in bytes. + </para> + </listitem> + <listitem> + <synopsis>int (*dumb_destroy)(struct drm_file *file_priv, struct drm_device *dev, + uint32_t handle);</synopsis> + <para> + The <methodname>dumb_destroy</methodname> operation destroys a dumb + object created by <methodname>dumb_create</methodname>. + </para> + </listitem> + <listitem> + <synopsis>int (*dumb_map_offset)(struct drm_file *file_priv, struct drm_device *dev, + uint32_t handle, uint64_t *offset);</synopsis> + <para> + The <methodname>dumb_map_offset</methodname> operation associates an + mmap fake offset with the object given by the handle and returns + it. Drivers must use the + <function>drm_gem_create_mmap_offset</function> function to + associate the fake offset as described in + <xref linkend="drm-gem-objects-mapping"/>. + </para> + </listitem> + </itemizedlist> + <para> + Note that dumb objects may not be used for gpu acceleration, as has been + attempted on some ARM embedded platforms. Such drivers really must have + a hardware-specific ioctl to allocate suitable buffer objects. + </para> + </sect2> + <sect2> + <title>Output Polling</title> + <synopsis>void (*output_poll_changed)(struct drm_device *dev);</synopsis> + <para> + This operation notifies the driver that the status of one or more + connectors has changed. Drivers that use the fb helper can just call the + <function>drm_fb_helper_hotplug_event</function> function to handle this + operation. + </para> + </sect2> + <sect2> + <title>Locking</title> + <para> + Beside some lookup structures with their own locking (which is hidden + behind the interface functions) most of the modeset state is protected + by the <code>dev-&lt;mode_config.lock</code> mutex and additionally + per-crtc locks to allow cursor updates, pageflips and similar operations + to occur concurrently with background tasks like output detection. + Operations which cross domains like a full modeset always grab all + locks. Drivers there need to protect resources shared between crtcs with + additional locking. They also need to be careful to always grab the + relevant crtc locks if a modset functions touches crtc state, e.g. for + load detection (which does only grab the <code>mode_config.lock</code> + to allow concurrent screen updates on live crtcs). + </para> + </sect2> + </sect1> + + <!-- Internals: kms initialization and cleanup --> + + <sect1 id="drm-kms-init"> + <title>KMS Initialization and Cleanup</title> + <para> + A KMS device is abstracted and exposed as a set of planes, CRTCs, encoders + and connectors. KMS drivers must thus create and initialize all those + objects at load time after initializing mode setting. + </para> + <sect2> + <title>CRTCs (struct <structname>drm_crtc</structname>)</title> + <para> + A CRTC is an abstraction representing a part of the chip that contains a + pointer to a scanout buffer. Therefore, the number of CRTCs available + determines how many independent scanout buffers can be active at any + given time. The CRTC structure contains several fields to support this: + a pointer to some video memory (abstracted as a frame buffer object), a + display mode, and an (x, y) offset into the video memory to support + panning or configurations where one piece of video memory spans multiple + CRTCs. + </para> + <sect3> + <title>CRTC Initialization</title> + <para> + A KMS device must create and register at least one struct + <structname>drm_crtc</structname> instance. The instance is allocated + and zeroed by the driver, possibly as part of a larger structure, and + registered with a call to <function>drm_crtc_init</function> with a + pointer to CRTC functions. + </para> + </sect3> + <sect3 id="drm-kms-crtcops"> + <title>CRTC Operations</title> + <sect4> + <title>Set Configuration</title> + <synopsis>int (*set_config)(struct drm_mode_set *set);</synopsis> + <para> + Apply a new CRTC configuration to the device. The configuration + specifies a CRTC, a frame buffer to scan out from, a (x,y) position in + the frame buffer, a display mode and an array of connectors to drive + with the CRTC if possible. + </para> + <para> + If the frame buffer specified in the configuration is NULL, the driver + must detach all encoders connected to the CRTC and all connectors + attached to those encoders and disable them. + </para> + <para> + This operation is called with the mode config lock held. + </para> + <note><para> + Note that the drm core has no notion of restoring the mode setting + state after resume, since all resume handling is in the full + responsibility of the driver. The common mode setting helper library + though provides a helper which can be used for this: + <function>drm_helper_resume_force_mode</function>. + </para></note> + </sect4> + <sect4> + <title>Page Flipping</title> + <synopsis>int (*page_flip)(struct drm_crtc *crtc, struct drm_framebuffer *fb, + struct drm_pending_vblank_event *event);</synopsis> + <para> + Schedule a page flip to the given frame buffer for the CRTC. This + operation is called with the mode config mutex held. + </para> + <para> + Page flipping is a synchronization mechanism that replaces the frame + buffer being scanned out by the CRTC with a new frame buffer during + vertical blanking, avoiding tearing. When an application requests a page + flip the DRM core verifies that the new frame buffer is large enough to + be scanned out by the CRTC in the currently configured mode and then + calls the CRTC <methodname>page_flip</methodname> operation with a + pointer to the new frame buffer. + </para> + <para> + The <methodname>page_flip</methodname> operation schedules a page flip. + Once any pending rendering targeting the new frame buffer has + completed, the CRTC will be reprogrammed to display that frame buffer + after the next vertical refresh. The operation must return immediately + without waiting for rendering or page flip to complete and must block + any new rendering to the frame buffer until the page flip completes. + </para> + <para> + If a page flip can be successfully scheduled the driver must set the + <code>drm_crtc-&gt;fb</code> field to the new framebuffer pointed to + by <code>fb</code>. This is important so that the reference counting + on framebuffers stays balanced. + </para> + <para> + If a page flip is already pending, the + <methodname>page_flip</methodname> operation must return + -<errorname>EBUSY</errorname>. + </para> + <para> + To synchronize page flip to vertical blanking the driver will likely + need to enable vertical blanking interrupts. It should call + <function>drm_vblank_get</function> for that purpose, and call + <function>drm_vblank_put</function> after the page flip completes. + </para> + <para> + If the application has requested to be notified when page flip completes + the <methodname>page_flip</methodname> operation will be called with a + non-NULL <parameter>event</parameter> argument pointing to a + <structname>drm_pending_vblank_event</structname> instance. Upon page + flip completion the driver must call <methodname>drm_send_vblank_event</methodname> + to fill in the event and send to wake up any waiting processes. + This can be performed with + <programlisting><![CDATA[ + spin_lock_irqsave(&dev->event_lock, flags); + ... + drm_send_vblank_event(dev, pipe, event); + spin_unlock_irqrestore(&dev->event_lock, flags); + ]]></programlisting> + </para> + <note><para> + FIXME: Could drivers that don't need to wait for rendering to complete + just add the event to <literal>dev-&gt;vblank_event_list</literal> and + let the DRM core handle everything, as for "normal" vertical blanking + events? + </para></note> + <para> + While waiting for the page flip to complete, the + <literal>event-&gt;base.link</literal> list head can be used freely by + the driver to store the pending event in a driver-specific list. + </para> + <para> + If the file handle is closed before the event is signaled, drivers must + take care to destroy the event in their + <methodname>preclose</methodname> operation (and, if needed, call + <function>drm_vblank_put</function>). + </para> + </sect4> + <sect4> + <title>Miscellaneous</title> + <itemizedlist> + <listitem> + <synopsis>void (*set_property)(struct drm_crtc *crtc, + struct drm_property *property, uint64_t value);</synopsis> + <para> + Set the value of the given CRTC property to + <parameter>value</parameter>. See <xref linkend="drm-kms-properties"/> + for more information about properties. + </para> + </listitem> + <listitem> + <synopsis>void (*gamma_set)(struct drm_crtc *crtc, u16 *r, u16 *g, u16 *b, + uint32_t start, uint32_t size);</synopsis> + <para> + Apply a gamma table to the device. The operation is optional. + </para> + </listitem> + <listitem> + <synopsis>void (*destroy)(struct drm_crtc *crtc);</synopsis> + <para> + Destroy the CRTC when not needed anymore. See + <xref linkend="drm-kms-init"/>. + </para> + </listitem> + </itemizedlist> + </sect4> + </sect3> + </sect2> + <sect2> + <title>Planes (struct <structname>drm_plane</structname>)</title> + <para> + A plane represents an image source that can be blended with or overlayed + on top of a CRTC during the scanout process. Planes are associated with + a frame buffer to crop a portion of the image memory (source) and + optionally scale it to a destination size. The result is then blended + with or overlayed on top of a CRTC. + </para> + <para> + The DRM core recognizes three types of planes: + <itemizedlist> + <listitem> + DRM_PLANE_TYPE_PRIMARY represents a "main" plane for a CRTC. Primary + planes are the planes operated upon by CRTC modesetting and flipping + operations described in <xref linkend="drm-kms-crtcops"/>. + </listitem> + <listitem> + DRM_PLANE_TYPE_CURSOR represents a "cursor" plane for a CRTC. Cursor + planes are the planes operated upon by the DRM_IOCTL_MODE_CURSOR and + DRM_IOCTL_MODE_CURSOR2 ioctls. + </listitem> + <listitem> + DRM_PLANE_TYPE_OVERLAY represents all non-primary, non-cursor planes. + Some drivers refer to these types of planes as "sprites" internally. + </listitem> + </itemizedlist> + For compatibility with legacy userspace, only overlay planes are made + available to userspace by default. Userspace clients may set the + DRM_CLIENT_CAP_UNIVERSAL_PLANES client capability bit to indicate that + they wish to receive a universal plane list containing all plane types. + </para> + <sect3> + <title>Plane Initialization</title> + <para> + To create a plane, a KMS drivers allocates and + zeroes an instances of struct <structname>drm_plane</structname> + (possibly as part of a larger structure) and registers it with a call + to <function>drm_universal_plane_init</function>. The function takes a bitmask + of the CRTCs that can be associated with the plane, a pointer to the + plane functions, a list of format supported formats, and the type of + plane (primary, cursor, or overlay) being initialized. + </para> + <para> + Cursor and overlay planes are optional. All drivers should provide + one primary plane per CRTC (although this requirement may change in + the future); drivers that do not wish to provide special handling for + primary planes may make use of the helper functions described in + <xref linkend="drm-kms-planehelpers"/> to create and register a + primary plane with standard capabilities. + </para> + </sect3> + <sect3> + <title>Plane Operations</title> + <itemizedlist> + <listitem> + <synopsis>int (*update_plane)(struct drm_plane *plane, struct drm_crtc *crtc, + struct drm_framebuffer *fb, int crtc_x, int crtc_y, + unsigned int crtc_w, unsigned int crtc_h, + uint32_t src_x, uint32_t src_y, + uint32_t src_w, uint32_t src_h);</synopsis> + <para> + Enable and configure the plane to use the given CRTC and frame buffer. + </para> + <para> + The source rectangle in frame buffer memory coordinates is given by + the <parameter>src_x</parameter>, <parameter>src_y</parameter>, + <parameter>src_w</parameter> and <parameter>src_h</parameter> + parameters (as 16.16 fixed point values). Devices that don't support + subpixel plane coordinates can ignore the fractional part. + </para> + <para> + The destination rectangle in CRTC coordinates is given by the + <parameter>crtc_x</parameter>, <parameter>crtc_y</parameter>, + <parameter>crtc_w</parameter> and <parameter>crtc_h</parameter> + parameters (as integer values). Devices scale the source rectangle to + the destination rectangle. If scaling is not supported, and the source + rectangle size doesn't match the destination rectangle size, the + driver must return a -<errorname>EINVAL</errorname> error. + </para> + </listitem> + <listitem> + <synopsis>int (*disable_plane)(struct drm_plane *plane);</synopsis> + <para> + Disable the plane. The DRM core calls this method in response to a + DRM_IOCTL_MODE_SETPLANE ioctl call with the frame buffer ID set to 0. + Disabled planes must not be processed by the CRTC. + </para> + </listitem> + <listitem> + <synopsis>void (*destroy)(struct drm_plane *plane);</synopsis> + <para> + Destroy the plane when not needed anymore. See + <xref linkend="drm-kms-init"/>. + </para> + </listitem> + </itemizedlist> + </sect3> + </sect2> + <sect2> + <title>Encoders (struct <structname>drm_encoder</structname>)</title> + <para> + An encoder takes pixel data from a CRTC and converts it to a format + suitable for any attached connectors. On some devices, it may be + possible to have a CRTC send data to more than one encoder. In that + case, both encoders would receive data from the same scanout buffer, + resulting in a "cloned" display configuration across the connectors + attached to each encoder. + </para> + <sect3> + <title>Encoder Initialization</title> + <para> + As for CRTCs, a KMS driver must create, initialize and register at + least one struct <structname>drm_encoder</structname> instance. The + instance is allocated and zeroed by the driver, possibly as part of a + larger structure. + </para> + <para> + Drivers must initialize the struct <structname>drm_encoder</structname> + <structfield>possible_crtcs</structfield> and + <structfield>possible_clones</structfield> fields before registering the + encoder. Both fields are bitmasks of respectively the CRTCs that the + encoder can be connected to, and sibling encoders candidate for cloning. + </para> + <para> + After being initialized, the encoder must be registered with a call to + <function>drm_encoder_init</function>. The function takes a pointer to + the encoder functions and an encoder type. Supported types are + <itemizedlist> + <listitem> + DRM_MODE_ENCODER_DAC for VGA and analog on DVI-I/DVI-A + </listitem> + <listitem> + DRM_MODE_ENCODER_TMDS for DVI, HDMI and (embedded) DisplayPort + </listitem> + <listitem> + DRM_MODE_ENCODER_LVDS for display panels + </listitem> + <listitem> + DRM_MODE_ENCODER_TVDAC for TV output (Composite, S-Video, Component, + SCART) + </listitem> + <listitem> + DRM_MODE_ENCODER_VIRTUAL for virtual machine displays + </listitem> + </itemizedlist> + </para> + <para> + Encoders must be attached to a CRTC to be used. DRM drivers leave + encoders unattached at initialization time. Applications (or the fbdev + compatibility layer when implemented) are responsible for attaching the + encoders they want to use to a CRTC. + </para> + </sect3> + <sect3> + <title>Encoder Operations</title> + <itemizedlist> + <listitem> + <synopsis>void (*destroy)(struct drm_encoder *encoder);</synopsis> + <para> + Called to destroy the encoder when not needed anymore. See + <xref linkend="drm-kms-init"/>. + </para> + </listitem> + <listitem> + <synopsis>void (*set_property)(struct drm_plane *plane, + struct drm_property *property, uint64_t value);</synopsis> + <para> + Set the value of the given plane property to + <parameter>value</parameter>. See <xref linkend="drm-kms-properties"/> + for more information about properties. + </para> + </listitem> + </itemizedlist> + </sect3> + </sect2> + <sect2> + <title>Connectors (struct <structname>drm_connector</structname>)</title> + <para> + A connector is the final destination for pixel data on a device, and + usually connects directly to an external display device like a monitor + or laptop panel. A connector can only be attached to one encoder at a + time. The connector is also the structure where information about the + attached display is kept, so it contains fields for display data, EDID + data, DPMS &amp; connection status, and information about modes + supported on the attached displays. + </para> + <sect3> + <title>Connector Initialization</title> + <para> + Finally a KMS driver must create, initialize, register and attach at + least one struct <structname>drm_connector</structname> instance. The + instance is created as other KMS objects and initialized by setting the + following fields. + </para> + <variablelist> + <varlistentry> + <term><structfield>interlace_allowed</structfield></term> + <listitem><para> + Whether the connector can handle interlaced modes. + </para></listitem> + </varlistentry> + <varlistentry> + <term><structfield>doublescan_allowed</structfield></term> + <listitem><para> + Whether the connector can handle doublescan. + </para></listitem> + </varlistentry> + <varlistentry> + <term><structfield>display_info + </structfield></term> + <listitem><para> + Display information is filled from EDID information when a display + is detected. For non hot-pluggable displays such as flat panels in + embedded systems, the driver should initialize the + <structfield>display_info</structfield>.<structfield>width_mm</structfield> + and + <structfield>display_info</structfield>.<structfield>height_mm</structfield> + fields with the physical size of the display. + </para></listitem> + </varlistentry> + <varlistentry> + <term id="drm-kms-connector-polled"><structfield>polled</structfield></term> + <listitem><para> + Connector polling mode, a combination of + <variablelist> + <varlistentry> + <term>DRM_CONNECTOR_POLL_HPD</term> + <listitem><para> + The connector generates hotplug events and doesn't need to be + periodically polled. The CONNECT and DISCONNECT flags must not + be set together with the HPD flag. + </para></listitem> + </varlistentry> + <varlistentry> + <term>DRM_CONNECTOR_POLL_CONNECT</term> + <listitem><para> + Periodically poll the connector for connection. + </para></listitem> + </varlistentry> + <varlistentry> + <term>DRM_CONNECTOR_POLL_DISCONNECT</term> + <listitem><para> + Periodically poll the connector for disconnection. + </para></listitem> + </varlistentry> + </variablelist> + Set to 0 for connectors that don't support connection status + discovery. + </para></listitem> + </varlistentry> + </variablelist> + <para> + The connector is then registered with a call to + <function>drm_connector_init</function> with a pointer to the connector + functions and a connector type, and exposed through sysfs with a call to + <function>drm_connector_register</function>. + </para> + <para> + Supported connector types are + <itemizedlist> + <listitem>DRM_MODE_CONNECTOR_VGA</listitem> + <listitem>DRM_MODE_CONNECTOR_DVII</listitem> + <listitem>DRM_MODE_CONNECTOR_DVID</listitem> + <listitem>DRM_MODE_CONNECTOR_DVIA</listitem> + <listitem>DRM_MODE_CONNECTOR_Composite</listitem> + <listitem>DRM_MODE_CONNECTOR_SVIDEO</listitem> + <listitem>DRM_MODE_CONNECTOR_LVDS</listitem> + <listitem>DRM_MODE_CONNECTOR_Component</listitem> + <listitem>DRM_MODE_CONNECTOR_9PinDIN</listitem> + <listitem>DRM_MODE_CONNECTOR_DisplayPort</listitem> + <listitem>DRM_MODE_CONNECTOR_HDMIA</listitem> + <listitem>DRM_MODE_CONNECTOR_HDMIB</listitem> + <listitem>DRM_MODE_CONNECTOR_TV</listitem> + <listitem>DRM_MODE_CONNECTOR_eDP</listitem> + <listitem>DRM_MODE_CONNECTOR_VIRTUAL</listitem> + </itemizedlist> + </para> + <para> + Connectors must be attached to an encoder to be used. For devices that + map connectors to encoders 1:1, the connector should be attached at + initialization time with a call to + <function>drm_mode_connector_attach_encoder</function>. The driver must + also set the <structname>drm_connector</structname> + <structfield>encoder</structfield> field to point to the attached + encoder. + </para> + <para> + Finally, drivers must initialize the connectors state change detection + with a call to <function>drm_kms_helper_poll_init</function>. If at + least one connector is pollable but can't generate hotplug interrupts + (indicated by the DRM_CONNECTOR_POLL_CONNECT and + DRM_CONNECTOR_POLL_DISCONNECT connector flags), a delayed work will + automatically be queued to periodically poll for changes. Connectors + that can generate hotplug interrupts must be marked with the + DRM_CONNECTOR_POLL_HPD flag instead, and their interrupt handler must + call <function>drm_helper_hpd_irq_event</function>. The function will + queue a delayed work to check the state of all connectors, but no + periodic polling will be done. + </para> + </sect3> + <sect3> + <title>Connector Operations</title> + <note><para> + Unless otherwise state, all operations are mandatory. + </para></note> + <sect4> + <title>DPMS</title> + <synopsis>void (*dpms)(struct drm_connector *connector, int mode);</synopsis> + <para> + The DPMS operation sets the power state of a connector. The mode + argument is one of + <itemizedlist> + <listitem><para>DRM_MODE_DPMS_ON</para></listitem> + <listitem><para>DRM_MODE_DPMS_STANDBY</para></listitem> + <listitem><para>DRM_MODE_DPMS_SUSPEND</para></listitem> + <listitem><para>DRM_MODE_DPMS_OFF</para></listitem> + </itemizedlist> + </para> + <para> + In all but DPMS_ON mode the encoder to which the connector is attached + should put the display in low-power mode by driving its signals + appropriately. If more than one connector is attached to the encoder + care should be taken not to change the power state of other displays as + a side effect. Low-power mode should be propagated to the encoders and + CRTCs when all related connectors are put in low-power mode. + </para> + </sect4> + <sect4> + <title>Modes</title> + <synopsis>int (*fill_modes)(struct drm_connector *connector, uint32_t max_width, + uint32_t max_height);</synopsis> + <para> + Fill the mode list with all supported modes for the connector. If the + <parameter>max_width</parameter> and <parameter>max_height</parameter> + arguments are non-zero, the implementation must ignore all modes wider + than <parameter>max_width</parameter> or higher than + <parameter>max_height</parameter>. + </para> + <para> + The connector must also fill in this operation its + <structfield>display_info</structfield> + <structfield>width_mm</structfield> and + <structfield>height_mm</structfield> fields with the connected display + physical size in millimeters. The fields should be set to 0 if the value + isn't known or is not applicable (for instance for projector devices). + </para> + </sect4> + <sect4> + <title>Connection Status</title> + <para> + The connection status is updated through polling or hotplug events when + supported (see <xref linkend="drm-kms-connector-polled"/>). The status + value is reported to userspace through ioctls and must not be used + inside the driver, as it only gets initialized by a call to + <function>drm_mode_getconnector</function> from userspace. + </para> + <synopsis>enum drm_connector_status (*detect)(struct drm_connector *connector, + bool force);</synopsis> + <para> + Check to see if anything is attached to the connector. The + <parameter>force</parameter> parameter is set to false whilst polling or + to true when checking the connector due to user request. + <parameter>force</parameter> can be used by the driver to avoid + expensive, destructive operations during automated probing. + </para> + <para> + Return connector_status_connected if something is connected to the + connector, connector_status_disconnected if nothing is connected and + connector_status_unknown if the connection state isn't known. + </para> + <para> + Drivers should only return connector_status_connected if the connection + status has really been probed as connected. Connectors that can't detect + the connection status, or failed connection status probes, should return + connector_status_unknown. + </para> + </sect4> + <sect4> + <title>Miscellaneous</title> + <itemizedlist> + <listitem> + <synopsis>void (*set_property)(struct drm_connector *connector, + struct drm_property *property, uint64_t value);</synopsis> + <para> + Set the value of the given connector property to + <parameter>value</parameter>. See <xref linkend="drm-kms-properties"/> + for more information about properties. + </para> + </listitem> + <listitem> + <synopsis>void (*destroy)(struct drm_connector *connector);</synopsis> + <para> + Destroy the connector when not needed anymore. See + <xref linkend="drm-kms-init"/>. + </para> + </listitem> + </itemizedlist> + </sect4> + </sect3> + </sect2> + <sect2> + <title>Cleanup</title> + <para> + The DRM core manages its objects' lifetime. When an object is not needed + anymore the core calls its destroy function, which must clean up and + free every resource allocated for the object. Every + <function>drm_*_init</function> call must be matched with a + corresponding <function>drm_*_cleanup</function> call to cleanup CRTCs + (<function>drm_crtc_cleanup</function>), planes + (<function>drm_plane_cleanup</function>), encoders + (<function>drm_encoder_cleanup</function>) and connectors + (<function>drm_connector_cleanup</function>). Furthermore, connectors + that have been added to sysfs must be removed by a call to + <function>drm_connector_unregister</function> before calling + <function>drm_connector_cleanup</function>. + </para> + <para> + Connectors state change detection must be cleanup up with a call to + <function>drm_kms_helper_poll_fini</function>. + </para> + </sect2> + <sect2> + <title>Output discovery and initialization example</title> + <programlisting><![CDATA[ +void intel_crt_init(struct drm_device *dev) +{ + struct drm_connector *connector; + struct intel_output *intel_output; + + intel_output = kzalloc(sizeof(struct intel_output), GFP_KERNEL); + if (!intel_output) + return; + + connector = &intel_output->base; + drm_connector_init(dev, &intel_output->base, + &intel_crt_connector_funcs, DRM_MODE_CONNECTOR_VGA); + + drm_encoder_init(dev, &intel_output->enc, &intel_crt_enc_funcs, + DRM_MODE_ENCODER_DAC); + + drm_mode_connector_attach_encoder(&intel_output->base, + &intel_output->enc); + + /* Set up the DDC bus. */ + intel_output->ddc_bus = intel_i2c_create(dev, GPIOA, "CRTDDC_A"); + if (!intel_output->ddc_bus) { + dev_printk(KERN_ERR, &dev->pdev->dev, "DDC bus registration " + "failed.\n"); + return; + } + + intel_output->type = INTEL_OUTPUT_ANALOG; + connector->interlace_allowed = 0; + connector->doublescan_allowed = 0; + + drm_encoder_helper_add(&intel_output->enc, &intel_crt_helper_funcs); + drm_connector_helper_add(connector, &intel_crt_connector_helper_funcs); + + drm_connector_register(connector); +}]]></programlisting> + <para> + In the example above (taken from the i915 driver), a CRTC, connector and + encoder combination is created. A device-specific i2c bus is also + created for fetching EDID data and performing monitor detection. Once + the process is complete, the new connector is registered with sysfs to + make its properties available to applications. + </para> + </sect2> + <sect2> + <title>KMS API Functions</title> +!Edrivers/gpu/drm/drm_crtc.c + </sect2> + <sect2> + <title>KMS Data Structures</title> +!Iinclude/drm/drm_crtc.h + </sect2> + <sect2> + <title>KMS Locking</title> +!Pdrivers/gpu/drm/drm_modeset_lock.c kms locking +!Iinclude/drm/drm_modeset_lock.h +!Edrivers/gpu/drm/drm_modeset_lock.c + </sect2> + </sect1> + + <!-- Internals: kms helper functions --> + + <sect1> + <title>Mode Setting Helper Functions</title> + <para> + The plane, CRTC, encoder and connector functions provided by the drivers + implement the DRM API. They're called by the DRM core and ioctl handlers + to handle device state changes and configuration request. As implementing + those functions often requires logic not specific to drivers, mid-layer + helper functions are available to avoid duplicating boilerplate code. + </para> + <para> + The DRM core contains one mid-layer implementation. The mid-layer provides + implementations of several plane, CRTC, encoder and connector functions + (called from the top of the mid-layer) that pre-process requests and call + lower-level functions provided by the driver (at the bottom of the + mid-layer). For instance, the + <function>drm_crtc_helper_set_config</function> function can be used to + fill the struct <structname>drm_crtc_funcs</structname> + <structfield>set_config</structfield> field. When called, it will split + the <methodname>set_config</methodname> operation in smaller, simpler + operations and call the driver to handle them. + </para> + <para> + To use the mid-layer, drivers call <function>drm_crtc_helper_add</function>, + <function>drm_encoder_helper_add</function> and + <function>drm_connector_helper_add</function> functions to install their + mid-layer bottom operations handlers, and fill the + <structname>drm_crtc_funcs</structname>, + <structname>drm_encoder_funcs</structname> and + <structname>drm_connector_funcs</structname> structures with pointers to + the mid-layer top API functions. Installing the mid-layer bottom operation + handlers is best done right after registering the corresponding KMS object. + </para> + <para> + The mid-layer is not split between CRTC, encoder and connector operations. + To use it, a driver must provide bottom functions for all of the three KMS + entities. + </para> + <sect2> + <title>Helper Functions</title> + <itemizedlist> + <listitem> + <synopsis>int drm_crtc_helper_set_config(struct drm_mode_set *set);</synopsis> + <para> + The <function>drm_crtc_helper_set_config</function> helper function + is a CRTC <methodname>set_config</methodname> implementation. It + first tries to locate the best encoder for each connector by calling + the connector <methodname>best_encoder</methodname> helper + operation. + </para> + <para> + After locating the appropriate encoders, the helper function will + call the <methodname>mode_fixup</methodname> encoder and CRTC helper + operations to adjust the requested mode, or reject it completely in + which case an error will be returned to the application. If the new + configuration after mode adjustment is identical to the current + configuration the helper function will return without performing any + other operation. + </para> + <para> + If the adjusted mode is identical to the current mode but changes to + the frame buffer need to be applied, the + <function>drm_crtc_helper_set_config</function> function will call + the CRTC <methodname>mode_set_base</methodname> helper operation. If + the adjusted mode differs from the current mode, or if the + <methodname>mode_set_base</methodname> helper operation is not + provided, the helper function performs a full mode set sequence by + calling the <methodname>prepare</methodname>, + <methodname>mode_set</methodname> and + <methodname>commit</methodname> CRTC and encoder helper operations, + in that order. + </para> + </listitem> + <listitem> + <synopsis>void drm_helper_connector_dpms(struct drm_connector *connector, int mode);</synopsis> + <para> + The <function>drm_helper_connector_dpms</function> helper function + is a connector <methodname>dpms</methodname> implementation that + tracks power state of connectors. To use the function, drivers must + provide <methodname>dpms</methodname> helper operations for CRTCs + and encoders to apply the DPMS state to the device. + </para> + <para> + The mid-layer doesn't track the power state of CRTCs and encoders. + The <methodname>dpms</methodname> helper operations can thus be + called with a mode identical to the currently active mode. + </para> + </listitem> + <listitem> + <synopsis>int drm_helper_probe_single_connector_modes(struct drm_connector *connector, + uint32_t maxX, uint32_t maxY);</synopsis> + <para> + The <function>drm_helper_probe_single_connector_modes</function> helper + function is a connector <methodname>fill_modes</methodname> + implementation that updates the connection status for the connector + and then retrieves a list of modes by calling the connector + <methodname>get_modes</methodname> helper operation. + </para> + <para> + If the helper operation returns no mode, and if the connector status + is connector_status_connected, standard VESA DMT modes up to + 1024x768 are automatically added to the modes list by a call to + <function>drm_add_modes_noedid</function>. + </para> + <para> + The function then filters out modes larger than + <parameter>max_width</parameter> and <parameter>max_height</parameter> + if specified. It finally calls the optional connector + <methodname>mode_valid</methodname> helper operation for each mode in + the probed list to check whether the mode is valid for the connector. + </para> + </listitem> + </itemizedlist> + </sect2> + <sect2> + <title>CRTC Helper Operations</title> + <itemizedlist> + <listitem id="drm-helper-crtc-mode-fixup"> + <synopsis>bool (*mode_fixup)(struct drm_crtc *crtc, + const struct drm_display_mode *mode, + struct drm_display_mode *adjusted_mode);</synopsis> + <para> + Let CRTCs adjust the requested mode or reject it completely. This + operation returns true if the mode is accepted (possibly after being + adjusted) or false if it is rejected. + </para> + <para> + The <methodname>mode_fixup</methodname> operation should reject the + mode if it can't reasonably use it. The definition of "reasonable" + is currently fuzzy in this context. One possible behaviour would be + to set the adjusted mode to the panel timings when a fixed-mode + panel is used with hardware capable of scaling. Another behaviour + would be to accept any input mode and adjust it to the closest mode + supported by the hardware (FIXME: This needs to be clarified). + </para> + </listitem> + <listitem> + <synopsis>int (*mode_set_base)(struct drm_crtc *crtc, int x, int y, + struct drm_framebuffer *old_fb)</synopsis> + <para> + Move the CRTC on the current frame buffer (stored in + <literal>crtc-&gt;fb</literal>) to position (x,y). Any of the frame + buffer, x position or y position may have been modified. + </para> + <para> + This helper operation is optional. If not provided, the + <function>drm_crtc_helper_set_config</function> function will fall + back to the <methodname>mode_set</methodname> helper operation. + </para> + <note><para> + FIXME: Why are x and y passed as arguments, as they can be accessed + through <literal>crtc-&gt;x</literal> and + <literal>crtc-&gt;y</literal>? + </para></note> + </listitem> + <listitem> + <synopsis>void (*prepare)(struct drm_crtc *crtc);</synopsis> + <para> + Prepare the CRTC for mode setting. This operation is called after + validating the requested mode. Drivers use it to perform + device-specific operations required before setting the new mode. + </para> + </listitem> + <listitem> + <synopsis>int (*mode_set)(struct drm_crtc *crtc, struct drm_display_mode *mode, + struct drm_display_mode *adjusted_mode, int x, int y, + struct drm_framebuffer *old_fb);</synopsis> + <para> + Set a new mode, position and frame buffer. Depending on the device + requirements, the mode can be stored internally by the driver and + applied in the <methodname>commit</methodname> operation, or + programmed to the hardware immediately. + </para> + <para> + The <methodname>mode_set</methodname> operation returns 0 on success + or a negative error code if an error occurs. + </para> + </listitem> + <listitem> + <synopsis>void (*commit)(struct drm_crtc *crtc);</synopsis> + <para> + Commit a mode. This operation is called after setting the new mode. + Upon return the device must use the new mode and be fully + operational. + </para> + </listitem> + </itemizedlist> + </sect2> + <sect2> + <title>Encoder Helper Operations</title> + <itemizedlist> + <listitem> + <synopsis>bool (*mode_fixup)(struct drm_encoder *encoder, + const struct drm_display_mode *mode, + struct drm_display_mode *adjusted_mode);</synopsis> + <para> + Let encoders adjust the requested mode or reject it completely. This + operation returns true if the mode is accepted (possibly after being + adjusted) or false if it is rejected. See the + <link linkend="drm-helper-crtc-mode-fixup">mode_fixup CRTC helper + operation</link> for an explanation of the allowed adjustments. + </para> + </listitem> + <listitem> + <synopsis>void (*prepare)(struct drm_encoder *encoder);</synopsis> + <para> + Prepare the encoder for mode setting. This operation is called after + validating the requested mode. Drivers use it to perform + device-specific operations required before setting the new mode. + </para> + </listitem> + <listitem> + <synopsis>void (*mode_set)(struct drm_encoder *encoder, + struct drm_display_mode *mode, + struct drm_display_mode *adjusted_mode);</synopsis> + <para> + Set a new mode. Depending on the device requirements, the mode can + be stored internally by the driver and applied in the + <methodname>commit</methodname> operation, or programmed to the + hardware immediately. + </para> + </listitem> + <listitem> + <synopsis>void (*commit)(struct drm_encoder *encoder);</synopsis> + <para> + Commit a mode. This operation is called after setting the new mode. + Upon return the device must use the new mode and be fully + operational. + </para> + </listitem> + </itemizedlist> + </sect2> + <sect2> + <title>Connector Helper Operations</title> + <itemizedlist> + <listitem> + <synopsis>struct drm_encoder *(*best_encoder)(struct drm_connector *connector);</synopsis> + <para> + Return a pointer to the best encoder for the connecter. Device that + map connectors to encoders 1:1 simply return the pointer to the + associated encoder. This operation is mandatory. + </para> + </listitem> + <listitem> + <synopsis>int (*get_modes)(struct drm_connector *connector);</synopsis> + <para> + Fill the connector's <structfield>probed_modes</structfield> list + by parsing EDID data with <function>drm_add_edid_modes</function>, + adding standard VESA DMT modes with <function>drm_add_modes_noedid</function>, + or calling <function>drm_mode_probed_add</function> directly for every + supported mode and return the number of modes it has detected. This + operation is mandatory. + </para> + <para> + Note that the caller function will automatically add standard VESA + DMT modes up to 1024x768 if the <methodname>get_modes</methodname> + helper operation returns no mode and if the connector status is + connector_status_connected. There is no need to call + <function>drm_add_edid_modes</function> manually in that case. + </para> + <para> + When adding modes manually the driver creates each mode with a call to + <function>drm_mode_create</function> and must fill the following fields. + <itemizedlist> + <listitem> + <synopsis>__u32 type;</synopsis> + <para> + Mode type bitmask, a combination of + <variablelist> + <varlistentry> + <term>DRM_MODE_TYPE_BUILTIN</term> + <listitem><para>not used?</para></listitem> + </varlistentry> + <varlistentry> + <term>DRM_MODE_TYPE_CLOCK_C</term> + <listitem><para>not used?</para></listitem> + </varlistentry> + <varlistentry> + <term>DRM_MODE_TYPE_CRTC_C</term> + <listitem><para>not used?</para></listitem> + </varlistentry> + <varlistentry> + <term> + DRM_MODE_TYPE_PREFERRED - The preferred mode for the connector + </term> + <listitem> + <para>not used?</para> + </listitem> + </varlistentry> + <varlistentry> + <term>DRM_MODE_TYPE_DEFAULT</term> + <listitem><para>not used?</para></listitem> + </varlistentry> + <varlistentry> + <term>DRM_MODE_TYPE_USERDEF</term> + <listitem><para>not used?</para></listitem> + </varlistentry> + <varlistentry> + <term>DRM_MODE_TYPE_DRIVER</term> + <listitem> + <para> + The mode has been created by the driver (as opposed to + to user-created modes). + </para> + </listitem> + </varlistentry> + </variablelist> + Drivers must set the DRM_MODE_TYPE_DRIVER bit for all modes they + create, and set the DRM_MODE_TYPE_PREFERRED bit for the preferred + mode. + </para> + </listitem> + <listitem> + <synopsis>__u32 clock;</synopsis> + <para>Pixel clock frequency in kHz unit</para> + </listitem> + <listitem> + <synopsis>__u16 hdisplay, hsync_start, hsync_end, htotal; + __u16 vdisplay, vsync_start, vsync_end, vtotal;</synopsis> + <para>Horizontal and vertical timing information</para> + <screen><![CDATA[ + Active Front Sync Back + Region Porch Porch + <-----------------------><----------------><-------------><--------------> + + //////////////////////| + ////////////////////// | + ////////////////////// |.................. ................ + _______________ + + <----- [hv]display -----> + <------------- [hv]sync_start ------------> + <--------------------- [hv]sync_end ---------------------> + <-------------------------------- [hv]total -----------------------------> +]]></screen> + </listitem> + <listitem> + <synopsis>__u16 hskew; + __u16 vscan;</synopsis> + <para>Unknown</para> + </listitem> + <listitem> + <synopsis>__u32 flags;</synopsis> + <para> + Mode flags, a combination of + <variablelist> + <varlistentry> + <term>DRM_MODE_FLAG_PHSYNC</term> + <listitem><para> + Horizontal sync is active high + </para></listitem> + </varlistentry> + <varlistentry> + <term>DRM_MODE_FLAG_NHSYNC</term> + <listitem><para> + Horizontal sync is active low + </para></listitem> + </varlistentry> + <varlistentry> + <term>DRM_MODE_FLAG_PVSYNC</term> + <listitem><para> + Vertical sync is active high + </para></listitem> + </varlistentry> + <varlistentry> + <term>DRM_MODE_FLAG_NVSYNC</term> + <listitem><para> + Vertical sync is active low + </para></listitem> + </varlistentry> + <varlistentry> + <term>DRM_MODE_FLAG_INTERLACE</term> + <listitem><para> + Mode is interlaced + </para></listitem> + </varlistentry> + <varlistentry> + <term>DRM_MODE_FLAG_DBLSCAN</term> + <listitem><para> + Mode uses doublescan + </para></listitem> + </varlistentry> + <varlistentry> + <term>DRM_MODE_FLAG_CSYNC</term> + <listitem><para> + Mode uses composite sync + </para></listitem> + </varlistentry> + <varlistentry> + <term>DRM_MODE_FLAG_PCSYNC</term> + <listitem><para> + Composite sync is active high + </para></listitem> + </varlistentry> + <varlistentry> + <term>DRM_MODE_FLAG_NCSYNC</term> + <listitem><para> + Composite sync is active low + </para></listitem> + </varlistentry> + <varlistentry> + <term>DRM_MODE_FLAG_HSKEW</term> + <listitem><para> + hskew provided (not used?) + </para></listitem> + </varlistentry> + <varlistentry> + <term>DRM_MODE_FLAG_BCAST</term> + <listitem><para> + not used? + </para></listitem> + </varlistentry> + <varlistentry> + <term>DRM_MODE_FLAG_PIXMUX</term> + <listitem><para> + not used? + </para></listitem> + </varlistentry> + <varlistentry> + <term>DRM_MODE_FLAG_DBLCLK</term> + <listitem><para> + not used? + </para></listitem> + </varlistentry> + <varlistentry> + <term>DRM_MODE_FLAG_CLKDIV2</term> + <listitem><para> + ? + </para></listitem> + </varlistentry> + </variablelist> + </para> + <para> + Note that modes marked with the INTERLACE or DBLSCAN flags will be + filtered out by + <function>drm_helper_probe_single_connector_modes</function> if + the connector's <structfield>interlace_allowed</structfield> or + <structfield>doublescan_allowed</structfield> field is set to 0. + </para> + </listitem> + <listitem> + <synopsis>char name[DRM_DISPLAY_MODE_LEN];</synopsis> + <para> + Mode name. The driver must call + <function>drm_mode_set_name</function> to fill the mode name from + <structfield>hdisplay</structfield>, + <structfield>vdisplay</structfield> and interlace flag after + filling the corresponding fields. + </para> + </listitem> + </itemizedlist> + </para> + <para> + The <structfield>vrefresh</structfield> value is computed by + <function>drm_helper_probe_single_connector_modes</function>. + </para> + <para> + When parsing EDID data, <function>drm_add_edid_modes</function> fills the + connector <structfield>display_info</structfield> + <structfield>width_mm</structfield> and + <structfield>height_mm</structfield> fields. When creating modes + manually the <methodname>get_modes</methodname> helper operation must + set the <structfield>display_info</structfield> + <structfield>width_mm</structfield> and + <structfield>height_mm</structfield> fields if they haven't been set + already (for instance at initialization time when a fixed-size panel is + attached to the connector). The mode <structfield>width_mm</structfield> + and <structfield>height_mm</structfield> fields are only used internally + during EDID parsing and should not be set when creating modes manually. + </para> + </listitem> + <listitem> + <synopsis>int (*mode_valid)(struct drm_connector *connector, + struct drm_display_mode *mode);</synopsis> + <para> + Verify whether a mode is valid for the connector. Return MODE_OK for + supported modes and one of the enum drm_mode_status values (MODE_*) + for unsupported modes. This operation is optional. + </para> + <para> + As the mode rejection reason is currently not used beside for + immediately removing the unsupported mode, an implementation can + return MODE_BAD regardless of the exact reason why the mode is not + valid. + </para> + <note><para> + Note that the <methodname>mode_valid</methodname> helper operation is + only called for modes detected by the device, and + <emphasis>not</emphasis> for modes set by the user through the CRTC + <methodname>set_config</methodname> operation. + </para></note> + </listitem> + </itemizedlist> + </sect2> + <sect2> + <title>Atomic Modeset Helper Functions Reference</title> + <sect3> + <title>Overview</title> +!Pdrivers/gpu/drm/drm_atomic_helper.c overview + </sect3> + <sect3> + <title>Implementing Asynchronous Atomic Commit</title> +!Pdrivers/gpu/drm/drm_atomic_helper.c implementing async commit + </sect3> + <sect3> + <title>Atomic State Reset and Initialization</title> +!Pdrivers/gpu/drm/drm_atomic_helper.c atomic state reset and initialization + </sect3> +!Iinclude/drm/drm_atomic_helper.h +!Edrivers/gpu/drm/drm_atomic_helper.c + </sect2> + <sect2> + <title>Modeset Helper Functions Reference</title> +!Iinclude/drm/drm_crtc_helper.h +!Edrivers/gpu/drm/drm_crtc_helper.c +!Pdrivers/gpu/drm/drm_crtc_helper.c overview + </sect2> + <sect2> + <title>Output Probing Helper Functions Reference</title> +!Pdrivers/gpu/drm/drm_probe_helper.c output probing helper overview +!Edrivers/gpu/drm/drm_probe_helper.c + </sect2> + <sect2> + <title>fbdev Helper Functions Reference</title> +!Pdrivers/gpu/drm/drm_fb_helper.c fbdev helpers +!Edrivers/gpu/drm/drm_fb_helper.c +!Iinclude/drm/drm_fb_helper.h + </sect2> + <sect2> + <title>Display Port Helper Functions Reference</title> +!Pdrivers/gpu/drm/drm_dp_helper.c dp helpers +!Iinclude/drm/drm_dp_helper.h +!Edrivers/gpu/drm/drm_dp_helper.c + </sect2> + <sect2> + <title>Display Port MST Helper Functions Reference</title> +!Pdrivers/gpu/drm/drm_dp_mst_topology.c dp mst helper +!Iinclude/drm/drm_dp_mst_helper.h +!Edrivers/gpu/drm/drm_dp_mst_topology.c + </sect2> + <sect2> + <title>MIPI DSI Helper Functions Reference</title> +!Pdrivers/gpu/drm/drm_mipi_dsi.c dsi helpers +!Iinclude/drm/drm_mipi_dsi.h +!Edrivers/gpu/drm/drm_mipi_dsi.c + </sect2> + <sect2> + <title>EDID Helper Functions Reference</title> +!Edrivers/gpu/drm/drm_edid.c + </sect2> + <sect2> + <title>Rectangle Utilities Reference</title> +!Pinclude/drm/drm_rect.h rect utils +!Iinclude/drm/drm_rect.h +!Edrivers/gpu/drm/drm_rect.c + </sect2> + <sect2> + <title>Flip-work Helper Reference</title> +!Pinclude/drm/drm_flip_work.h flip utils +!Iinclude/drm/drm_flip_work.h +!Edrivers/gpu/drm/drm_flip_work.c + </sect2> + <sect2> + <title>HDMI Infoframes Helper Reference</title> + <para> + Strictly speaking this is not a DRM helper library but generally useable + by any driver interfacing with HDMI outputs like v4l or alsa drivers. + But it nicely fits into the overall topic of mode setting helper + libraries and hence is also included here. + </para> +!Iinclude/linux/hdmi.h +!Edrivers/video/hdmi.c + </sect2> + <sect2> + <title id="drm-kms-planehelpers">Plane Helper Reference</title> +!Edrivers/gpu/drm/drm_plane_helper.c +!Pdrivers/gpu/drm/drm_plane_helper.c overview + </sect2> + <sect2> + <title>Tile group</title> +!Pdrivers/gpu/drm/drm_crtc.c Tile group + </sect2> + <sect2> + <title>Bridges</title> + <sect3> + <title>Overview</title> +!Pdrivers/gpu/drm/drm_bridge.c overview + </sect3> + <sect3> + <title>Default bridge callback sequence</title> +!Pdrivers/gpu/drm/drm_bridge.c bridge callbacks + </sect3> +!Edrivers/gpu/drm/drm_bridge.c + </sect2> + </sect1> + + <!-- Internals: kms properties --> + + <sect1 id="drm-kms-properties"> + <title>KMS Properties</title> + <para> + Drivers may need to expose additional parameters to applications than + those described in the previous sections. KMS supports attaching + properties to CRTCs, connectors and planes and offers a userspace API to + list, get and set the property values. + </para> + <para> + Properties are identified by a name that uniquely defines the property + purpose, and store an associated value. For all property types except blob + properties the value is a 64-bit unsigned integer. + </para> + <para> + KMS differentiates between properties and property instances. Drivers + first create properties and then create and associate individual instances + of those properties to objects. A property can be instantiated multiple + times and associated with different objects. Values are stored in property + instances, and all other property information are stored in the property + and shared between all instances of the property. + </para> + <para> + Every property is created with a type that influences how the KMS core + handles the property. Supported property types are + <variablelist> + <varlistentry> + <term>DRM_MODE_PROP_RANGE</term> + <listitem><para>Range properties report their minimum and maximum + admissible values. The KMS core verifies that values set by + application fit in that range.</para></listitem> + </varlistentry> + <varlistentry> + <term>DRM_MODE_PROP_ENUM</term> + <listitem><para>Enumerated properties take a numerical value that + ranges from 0 to the number of enumerated values defined by the + property minus one, and associate a free-formed string name to each + value. Applications can retrieve the list of defined value-name pairs + and use the numerical value to get and set property instance values. + </para></listitem> + </varlistentry> + <varlistentry> + <term>DRM_MODE_PROP_BITMASK</term> + <listitem><para>Bitmask properties are enumeration properties that + additionally restrict all enumerated values to the 0..63 range. + Bitmask property instance values combine one or more of the + enumerated bits defined by the property.</para></listitem> + </varlistentry> + <varlistentry> + <term>DRM_MODE_PROP_BLOB</term> + <listitem><para>Blob properties store a binary blob without any format + restriction. The binary blobs are created as KMS standalone objects, + and blob property instance values store the ID of their associated + blob object.</para> + <para>Blob properties are only used for the connector EDID property + and cannot be created by drivers.</para></listitem> + </varlistentry> + </variablelist> + </para> + <para> + To create a property drivers call one of the following functions depending + on the property type. All property creation functions take property flags + and name, as well as type-specific arguments. + <itemizedlist> + <listitem> + <synopsis>struct drm_property *drm_property_create_range(struct drm_device *dev, int flags, + const char *name, + uint64_t min, uint64_t max);</synopsis> + <para>Create a range property with the given minimum and maximum + values.</para> + </listitem> + <listitem> + <synopsis>struct drm_property *drm_property_create_enum(struct drm_device *dev, int flags, + const char *name, + const struct drm_prop_enum_list *props, + int num_values);</synopsis> + <para>Create an enumerated property. The <parameter>props</parameter> + argument points to an array of <parameter>num_values</parameter> + value-name pairs.</para> + </listitem> + <listitem> + <synopsis>struct drm_property *drm_property_create_bitmask(struct drm_device *dev, + int flags, const char *name, + const struct drm_prop_enum_list *props, + int num_values);</synopsis> + <para>Create a bitmask property. The <parameter>props</parameter> + argument points to an array of <parameter>num_values</parameter> + value-name pairs.</para> + </listitem> + </itemizedlist> + </para> + <para> + Properties can additionally be created as immutable, in which case they + will be read-only for applications but can be modified by the driver. To + create an immutable property drivers must set the DRM_MODE_PROP_IMMUTABLE + flag at property creation time. + </para> + <para> + When no array of value-name pairs is readily available at property + creation time for enumerated or range properties, drivers can create + the property using the <function>drm_property_create</function> function + and manually add enumeration value-name pairs by calling the + <function>drm_property_add_enum</function> function. Care must be taken to + properly specify the property type through the <parameter>flags</parameter> + argument. + </para> + <para> + After creating properties drivers can attach property instances to CRTC, + connector and plane objects by calling the + <function>drm_object_attach_property</function>. The function takes a + pointer to the target object, a pointer to the previously created property + and an initial instance value. + </para> + <sect2> + <title>Existing KMS Properties</title> + <para> + The following table gives description of drm properties exposed by various + modules/drivers. + </para> + <table border="1" cellpadding="0" cellspacing="0"> + <tbody> + <tr style="font-weight: bold;"> + <td valign="top" >Owner Module/Drivers</td> + <td valign="top" >Group</td> + <td valign="top" >Property Name</td> + <td valign="top" >Type</td> + <td valign="top" >Property Values</td> + <td valign="top" >Object attached</td> + <td valign="top" >Description/Restrictions</td> + </tr> + <tr> + <td rowspan="37" valign="top" >DRM</td> + <td valign="top" >Generic</td> + <td valign="top" >“rotation”</td> + <td valign="top" >BITMASK</td> + <td valign="top" >{ 0, "rotate-0" }, + { 1, "rotate-90" }, + { 2, "rotate-180" }, + { 3, "rotate-270" }, + { 4, "reflect-x" }, + { 5, "reflect-y" }</td> + <td valign="top" >CRTC, Plane</td> + <td valign="top" >rotate-(degrees) rotates the image by the specified amount in degrees + in counter clockwise direction. reflect-x and reflect-y reflects the + image along the specified axis prior to rotation</td> + </tr> + <tr> + <td rowspan="5" valign="top" >Connector</td> + <td valign="top" >“EDID”</td> + <td valign="top" >BLOB | IMMUTABLE</td> + <td valign="top" >0</td> + <td valign="top" >Connector</td> + <td valign="top" >Contains id of edid blob ptr object.</td> + </tr> + <tr> + <td valign="top" >“DPMS”</td> + <td valign="top" >ENUM</td> + <td valign="top" >{ “On”, “Standby”, “Suspend”, “Off” }</td> + <td valign="top" >Connector</td> + <td valign="top" >Contains DPMS operation mode value.</td> + </tr> + <tr> + <td valign="top" >“PATH”</td> + <td valign="top" >BLOB | IMMUTABLE</td> + <td valign="top" >0</td> + <td valign="top" >Connector</td> + <td valign="top" >Contains topology path to a connector.</td> + </tr> + <tr> + <td valign="top" >“TILE”</td> + <td valign="top" >BLOB | IMMUTABLE</td> + <td valign="top" >0</td> + <td valign="top" >Connector</td> + <td valign="top" >Contains tiling information for a connector.</td> + </tr> + <tr> + <td valign="top" >“CRTC_ID”</td> + <td valign="top" >OBJECT</td> + <td valign="top" >DRM_MODE_OBJECT_CRTC</td> + <td valign="top" >Connector</td> + <td valign="top" >CRTC that connector is attached to (atomic)</td> + </tr> + <tr> + <td rowspan="11" valign="top" >Plane</td> + <td valign="top" >“type”</td> + <td valign="top" >ENUM | IMMUTABLE</td> + <td valign="top" >{ "Overlay", "Primary", "Cursor" }</td> + <td valign="top" >Plane</td> + <td valign="top" >Plane type</td> + </tr> + <tr> + <td valign="top" >“SRC_X”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=UINT_MAX</td> + <td valign="top" >Plane</td> + <td valign="top" >Scanout source x coordinate in 16.16 fixed point (atomic)</td> + </tr> + <tr> + <td valign="top" >“SRC_Y”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=UINT_MAX</td> + <td valign="top" >Plane</td> + <td valign="top" >Scanout source y coordinate in 16.16 fixed point (atomic)</td> + </tr> + <tr> + <td valign="top" >“SRC_W”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=UINT_MAX</td> + <td valign="top" >Plane</td> + <td valign="top" >Scanout source width in 16.16 fixed point (atomic)</td> + </tr> + <tr> + <td valign="top" >“SRC_H”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=UINT_MAX</td> + <td valign="top" >Plane</td> + <td valign="top" >Scanout source height in 16.16 fixed point (atomic)</td> + </tr> + <tr> + <td valign="top" >“CRTC_X”</td> + <td valign="top" >SIGNED_RANGE</td> + <td valign="top" >Min=INT_MIN, Max=INT_MAX</td> + <td valign="top" >Plane</td> + <td valign="top" >Scanout CRTC (destination) x coordinate (atomic)</td> + </tr> + <tr> + <td valign="top" >“CRTC_Y”</td> + <td valign="top" >SIGNED_RANGE</td> + <td valign="top" >Min=INT_MIN, Max=INT_MAX</td> + <td valign="top" >Plane</td> + <td valign="top" >Scanout CRTC (destination) y coordinate (atomic)</td> + </tr> + <tr> + <td valign="top" >“CRTC_W”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=UINT_MAX</td> + <td valign="top" >Plane</td> + <td valign="top" >Scanout CRTC (destination) width (atomic)</td> + </tr> + <tr> + <td valign="top" >“CRTC_H”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=UINT_MAX</td> + <td valign="top" >Plane</td> + <td valign="top" >Scanout CRTC (destination) height (atomic)</td> + </tr> + <tr> + <td valign="top" >“FB_ID”</td> + <td valign="top" >OBJECT</td> + <td valign="top" >DRM_MODE_OBJECT_FB</td> + <td valign="top" >Plane</td> + <td valign="top" >Scanout framebuffer (atomic)</td> + </tr> + <tr> + <td valign="top" >“CRTC_ID”</td> + <td valign="top" >OBJECT</td> + <td valign="top" >DRM_MODE_OBJECT_CRTC</td> + <td valign="top" >Plane</td> + <td valign="top" >CRTC that plane is attached to (atomic)</td> + </tr> + <tr> + <td rowspan="2" valign="top" >DVI-I</td> + <td valign="top" >“subconnector”</td> + <td valign="top" >ENUM</td> + <td valign="top" >{ “Unknown”, “DVI-D”, “DVI-A” }</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“select subconnector”</td> + <td valign="top" >ENUM</td> + <td valign="top" >{ “Automatic”, “DVI-D”, “DVI-A” }</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td rowspan="13" valign="top" >TV</td> + <td valign="top" >“subconnector”</td> + <td valign="top" >ENUM</td> + <td valign="top" >{ "Unknown", "Composite", "SVIDEO", "Component", "SCART" }</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“select subconnector”</td> + <td valign="top" >ENUM</td> + <td valign="top" >{ "Automatic", "Composite", "SVIDEO", "Component", "SCART" }</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“mode”</td> + <td valign="top" >ENUM</td> + <td valign="top" >{ "NTSC_M", "NTSC_J", "NTSC_443", "PAL_B" } etc.</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“left margin”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=100</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“right margin”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=100</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“top margin”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=100</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“bottom margin”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=100</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“brightness”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=100</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“contrast”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=100</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“flicker reduction”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=100</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“overscan”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=100</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“saturation”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=100</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“hue”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=100</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td rowspan="2" valign="top" >Virtual GPU</td> + <td valign="top" >“suggested X”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=0xffffffff</td> + <td valign="top" >Connector</td> + <td valign="top" >property to suggest an X offset for a connector</td> + </tr> + <tr> + <td valign="top" >“suggested Y”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=0xffffffff</td> + <td valign="top" >Connector</td> + <td valign="top" >property to suggest an Y offset for a connector</td> + </tr> + <tr> + <td rowspan="3" valign="top" >Optional</td> + <td valign="top" >“scaling mode”</td> + <td valign="top" >ENUM</td> + <td valign="top" >{ "None", "Full", "Center", "Full aspect" }</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >"aspect ratio"</td> + <td valign="top" >ENUM</td> + <td valign="top" >{ "None", "4:3", "16:9" }</td> + <td valign="top" >Connector</td> + <td valign="top" >DRM property to set aspect ratio from user space app. + This enum is made generic to allow addition of custom aspect + ratios.</td> + </tr> + <tr> + <td valign="top" >“dirty”</td> + <td valign="top" >ENUM | IMMUTABLE</td> + <td valign="top" >{ "Off", "On", "Annotate" }</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td rowspan="20" valign="top" >i915</td> + <td rowspan="2" valign="top" >Generic</td> + <td valign="top" >"Broadcast RGB"</td> + <td valign="top" >ENUM</td> + <td valign="top" >{ "Automatic", "Full", "Limited 16:235" }</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“audio”</td> + <td valign="top" >ENUM</td> + <td valign="top" >{ "force-dvi", "off", "auto", "on" }</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td rowspan="17" valign="top" >SDVO-TV</td> + <td valign="top" >“mode”</td> + <td valign="top" >ENUM</td> + <td valign="top" >{ "NTSC_M", "NTSC_J", "NTSC_443", "PAL_B" } etc.</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >"left_margin"</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >"right_margin"</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >"top_margin"</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >"bottom_margin"</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“hpos”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“vpos”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“contrast”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“saturation”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“hue”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“sharpness”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“flicker_filter”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“flicker_filter_adaptive”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“flicker_filter_2d”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“tv_chroma_filter”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“tv_luma_filter”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“dot_crawl”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=1</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >SDVO-TV/LVDS</td> + <td valign="top" >“brightness”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td rowspan="2" valign="top" >CDV gma-500</td> + <td rowspan="2" valign="top" >Generic</td> + <td valign="top" >"Broadcast RGB"</td> + <td valign="top" >ENUM</td> + <td valign="top" >{ “Full”, “Limited 16:235” }</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >"Broadcast RGB"</td> + <td valign="top" >ENUM</td> + <td valign="top" >{ “off”, “auto”, “on” }</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td rowspan="19" valign="top" >Poulsbo</td> + <td rowspan="1" valign="top" >Generic</td> + <td valign="top" >“backlight”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=100</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td rowspan="17" valign="top" >SDVO-TV</td> + <td valign="top" >“mode”</td> + <td valign="top" >ENUM</td> + <td valign="top" >{ "NTSC_M", "NTSC_J", "NTSC_443", "PAL_B" } etc.</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >"left_margin"</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >"right_margin"</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >"top_margin"</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >"bottom_margin"</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“hpos”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“vpos”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“contrast”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“saturation”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“hue”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“sharpness”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“flicker_filter”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“flicker_filter_adaptive”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“flicker_filter_2d”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“tv_chroma_filter”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“tv_luma_filter”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“dot_crawl”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=1</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >SDVO-TV/LVDS</td> + <td valign="top" >“brightness”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max= SDVO dependent</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td rowspan="11" valign="top" >armada</td> + <td rowspan="2" valign="top" >CRTC</td> + <td valign="top" >"CSC_YUV"</td> + <td valign="top" >ENUM</td> + <td valign="top" >{ "Auto" , "CCIR601", "CCIR709" }</td> + <td valign="top" >CRTC</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >"CSC_RGB"</td> + <td valign="top" >ENUM</td> + <td valign="top" >{ "Auto", "Computer system", "Studio" }</td> + <td valign="top" >CRTC</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td rowspan="9" valign="top" >Overlay</td> + <td valign="top" >"colorkey"</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=0xffffff</td> + <td valign="top" >Plane</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >"colorkey_min"</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=0xffffff</td> + <td valign="top" >Plane</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >"colorkey_max"</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=0xffffff</td> + <td valign="top" >Plane</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >"colorkey_val"</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=0xffffff</td> + <td valign="top" >Plane</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >"colorkey_alpha"</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=0xffffff</td> + <td valign="top" >Plane</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >"colorkey_mode"</td> + <td valign="top" >ENUM</td> + <td valign="top" >{ "disabled", "Y component", "U component" + , "V component", "RGB", “R component", "G component", "B component" }</td> + <td valign="top" >Plane</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >"brightness"</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=256 + 255</td> + <td valign="top" >Plane</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >"contrast"</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=0x7fff</td> + <td valign="top" >Plane</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >"saturation"</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=0x7fff</td> + <td valign="top" >Plane</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td rowspan="2" valign="top" >exynos</td> + <td valign="top" >CRTC</td> + <td valign="top" >“mode”</td> + <td valign="top" >ENUM</td> + <td valign="top" >{ "normal", "blank" }</td> + <td valign="top" >CRTC</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >Overlay</td> + <td valign="top" >“zpos”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=MAX_PLANE-1</td> + <td valign="top" >Plane</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td rowspan="2" valign="top" >i2c/ch7006_drv</td> + <td valign="top" >Generic</td> + <td valign="top" >“scale”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=2</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td rowspan="1" valign="top" >TV</td> + <td valign="top" >“mode”</td> + <td valign="top" >ENUM</td> + <td valign="top" >{ "PAL", "PAL-M","PAL-N"}, ”PAL-Nc" + , "PAL-60", "NTSC-M", "NTSC-J" }</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td rowspan="15" valign="top" >nouveau</td> + <td rowspan="6" valign="top" >NV10 Overlay</td> + <td valign="top" >"colorkey"</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=0x01ffffff</td> + <td valign="top" >Plane</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“contrast”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=8192-1</td> + <td valign="top" >Plane</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“brightness”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=1024</td> + <td valign="top" >Plane</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“hue”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=359</td> + <td valign="top" >Plane</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“saturation”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=8192-1</td> + <td valign="top" >Plane</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“iturbt_709”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=1</td> + <td valign="top" >Plane</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td rowspan="2" valign="top" >Nv04 Overlay</td> + <td valign="top" >“colorkey”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=0x01ffffff</td> + <td valign="top" >Plane</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“brightness”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=1024</td> + <td valign="top" >Plane</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td rowspan="7" valign="top" >Display</td> + <td valign="top" >“dithering mode”</td> + <td valign="top" >ENUM</td> + <td valign="top" >{ "auto", "off", "on" }</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“dithering depth”</td> + <td valign="top" >ENUM</td> + <td valign="top" >{ "auto", "off", "on", "static 2x2", "dynamic 2x2", "temporal" }</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“underscan”</td> + <td valign="top" >ENUM</td> + <td valign="top" >{ "auto", "6 bpc", "8 bpc" }</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“underscan hborder”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=128</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“underscan vborder”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=128</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“vibrant hue”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=180</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >“color vibrance”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=200</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >omap</td> + <td valign="top" >Generic</td> + <td valign="top" >“zorder”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=3</td> + <td valign="top" >CRTC, Plane</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >qxl</td> + <td valign="top" >Generic</td> + <td valign="top" >“hotplug_mode_update"</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=1</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td rowspan="9" valign="top" >radeon</td> + <td valign="top" >DVI-I</td> + <td valign="top" >“coherent”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=1</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >DAC enable load detect</td> + <td valign="top" >“load detection”</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=1</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >TV Standard</td> + <td valign="top" >"tv standard"</td> + <td valign="top" >ENUM</td> + <td valign="top" >{ "ntsc", "pal", "pal-m", "pal-60", "ntsc-j" + , "scart-pal", "pal-cn", "secam" }</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >legacy TMDS PLL detect</td> + <td valign="top" >"tmds_pll"</td> + <td valign="top" >ENUM</td> + <td valign="top" >{ "driver", "bios" }</td> + <td valign="top" >-</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td rowspan="3" valign="top" >Underscan</td> + <td valign="top" >"underscan"</td> + <td valign="top" >ENUM</td> + <td valign="top" >{ "off", "on", "auto" }</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >"underscan hborder"</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=128</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >"underscan vborder"</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=128</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >Audio</td> + <td valign="top" >“audio”</td> + <td valign="top" >ENUM</td> + <td valign="top" >{ "off", "on", "auto" }</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >FMT Dithering</td> + <td valign="top" >“dither”</td> + <td valign="top" >ENUM</td> + <td valign="top" >{ "off", "on" }</td> + <td valign="top" >Connector</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td rowspan="3" valign="top" >rcar-du</td> + <td rowspan="3" valign="top" >Generic</td> + <td valign="top" >"alpha"</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=255</td> + <td valign="top" >Plane</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >"colorkey"</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=0x01ffffff</td> + <td valign="top" >Plane</td> + <td valign="top" >TBD</td> + </tr> + <tr> + <td valign="top" >"zpos"</td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=1, Max=7</td> + <td valign="top" >Plane</td> + <td valign="top" >TBD</td> + </tr> + </tbody> + </table> + </sect2> + </sect1> + + <!-- Internals: vertical blanking --> + + <sect1 id="drm-vertical-blank"> + <title>Vertical Blanking</title> + <para> + Vertical blanking plays a major role in graphics rendering. To achieve + tear-free display, users must synchronize page flips and/or rendering to + vertical blanking. The DRM API offers ioctls to perform page flips + synchronized to vertical blanking and wait for vertical blanking. + </para> + <para> + The DRM core handles most of the vertical blanking management logic, which + involves filtering out spurious interrupts, keeping race-free blanking + counters, coping with counter wrap-around and resets and keeping use + counts. It relies on the driver to generate vertical blanking interrupts + and optionally provide a hardware vertical blanking counter. Drivers must + implement the following operations. + </para> + <itemizedlist> + <listitem> + <synopsis>int (*enable_vblank) (struct drm_device *dev, int crtc); +void (*disable_vblank) (struct drm_device *dev, int crtc);</synopsis> + <para> + Enable or disable vertical blanking interrupts for the given CRTC. + </para> + </listitem> + <listitem> + <synopsis>u32 (*get_vblank_counter) (struct drm_device *dev, int crtc);</synopsis> + <para> + Retrieve the value of the vertical blanking counter for the given + CRTC. If the hardware maintains a vertical blanking counter its value + should be returned. Otherwise drivers can use the + <function>drm_vblank_count</function> helper function to handle this + operation. + </para> + </listitem> + </itemizedlist> + <para> + Drivers must initialize the vertical blanking handling core with a call to + <function>drm_vblank_init</function> in their + <methodname>load</methodname> operation. The function will set the struct + <structname>drm_device</structname> + <structfield>vblank_disable_allowed</structfield> field to 0. This will + keep vertical blanking interrupts enabled permanently until the first mode + set operation, where <structfield>vblank_disable_allowed</structfield> is + set to 1. The reason behind this is not clear. Drivers can set the field + to 1 after <function>calling drm_vblank_init</function> to make vertical + blanking interrupts dynamically managed from the beginning. + </para> + <para> + Vertical blanking interrupts can be enabled by the DRM core or by drivers + themselves (for instance to handle page flipping operations). The DRM core + maintains a vertical blanking use count to ensure that the interrupts are + not disabled while a user still needs them. To increment the use count, + drivers call <function>drm_vblank_get</function>. Upon return vertical + blanking interrupts are guaranteed to be enabled. + </para> + <para> + To decrement the use count drivers call + <function>drm_vblank_put</function>. Only when the use count drops to zero + will the DRM core disable the vertical blanking interrupts after a delay + by scheduling a timer. The delay is accessible through the vblankoffdelay + module parameter or the <varname>drm_vblank_offdelay</varname> global + variable and expressed in milliseconds. Its default value is 5000 ms. + Zero means never disable, and a negative value means disable immediately. + Drivers may override the behaviour by setting the + <structname>drm_device</structname> + <structfield>vblank_disable_immediate</structfield> flag, which when set + causes vblank interrupts to be disabled immediately regardless of the + drm_vblank_offdelay value. The flag should only be set if there's a + properly working hardware vblank counter present. + </para> + <para> + When a vertical blanking interrupt occurs drivers only need to call the + <function>drm_handle_vblank</function> function to account for the + interrupt. + </para> + <para> + Resources allocated by <function>drm_vblank_init</function> must be freed + with a call to <function>drm_vblank_cleanup</function> in the driver + <methodname>unload</methodname> operation handler. + </para> + <sect2> + <title>Vertical Blanking and Interrupt Handling Functions Reference</title> +!Edrivers/gpu/drm/drm_irq.c +!Finclude/drm/drmP.h drm_crtc_vblank_waitqueue + </sect2> + </sect1> + + <!-- Internals: open/close, file operations and ioctls --> + + <sect1> + <title>Open/Close, File Operations and IOCTLs</title> + <sect2> + <title>Open and Close</title> + <synopsis>int (*firstopen) (struct drm_device *); +void (*lastclose) (struct drm_device *); +int (*open) (struct drm_device *, struct drm_file *); +void (*preclose) (struct drm_device *, struct drm_file *); +void (*postclose) (struct drm_device *, struct drm_file *);</synopsis> + <abstract>Open and close handlers. None of those methods are mandatory. + </abstract> + <para> + The <methodname>firstopen</methodname> method is called by the DRM core + for legacy UMS (User Mode Setting) drivers only when an application + opens a device that has no other opened file handle. UMS drivers can + implement it to acquire device resources. KMS drivers can't use the + method and must acquire resources in the <methodname>load</methodname> + method instead. + </para> + <para> + Similarly the <methodname>lastclose</methodname> method is called when + the last application holding a file handle opened on the device closes + it, for both UMS and KMS drivers. Additionally, the method is also + called at module unload time or, for hot-pluggable devices, when the + device is unplugged. The <methodname>firstopen</methodname> and + <methodname>lastclose</methodname> calls can thus be unbalanced. + </para> + <para> + The <methodname>open</methodname> method is called every time the device + is opened by an application. Drivers can allocate per-file private data + in this method and store them in the struct + <structname>drm_file</structname> <structfield>driver_priv</structfield> + field. Note that the <methodname>open</methodname> method is called + before <methodname>firstopen</methodname>. + </para> + <para> + The close operation is split into <methodname>preclose</methodname> and + <methodname>postclose</methodname> methods. Drivers must stop and + cleanup all per-file operations in the <methodname>preclose</methodname> + method. For instance pending vertical blanking and page flip events must + be cancelled. No per-file operation is allowed on the file handle after + returning from the <methodname>preclose</methodname> method. + </para> + <para> + Finally the <methodname>postclose</methodname> method is called as the + last step of the close operation, right before calling the + <methodname>lastclose</methodname> method if no other open file handle + exists for the device. Drivers that have allocated per-file private data + in the <methodname>open</methodname> method should free it here. + </para> + <para> + The <methodname>lastclose</methodname> method should restore CRTC and + plane properties to default value, so that a subsequent open of the + device will not inherit state from the previous user. It can also be + used to execute delayed power switching state changes, e.g. in + conjunction with the vga_switcheroo infrastructure. Beyond that KMS + drivers should not do any further cleanup. Only legacy UMS drivers might + need to clean up device state so that the vga console or an independent + fbdev driver could take over. + </para> + </sect2> + <sect2> + <title>File Operations</title> + <synopsis>const struct file_operations *fops</synopsis> + <abstract>File operations for the DRM device node.</abstract> + <para> + Drivers must define the file operations structure that forms the DRM + userspace API entry point, even though most of those operations are + implemented in the DRM core. The <methodname>open</methodname>, + <methodname>release</methodname> and <methodname>ioctl</methodname> + operations are handled by + <programlisting> + .owner = THIS_MODULE, + .open = drm_open, + .release = drm_release, + .unlocked_ioctl = drm_ioctl, + #ifdef CONFIG_COMPAT + .compat_ioctl = drm_compat_ioctl, + #endif + </programlisting> + </para> + <para> + Drivers that implement private ioctls that requires 32/64bit + compatibility support must provide their own + <methodname>compat_ioctl</methodname> handler that processes private + ioctls and calls <function>drm_compat_ioctl</function> for core ioctls. + </para> + <para> + The <methodname>read</methodname> and <methodname>poll</methodname> + operations provide support for reading DRM events and polling them. They + are implemented by + <programlisting> + .poll = drm_poll, + .read = drm_read, + .llseek = no_llseek, + </programlisting> + </para> + <para> + The memory mapping implementation varies depending on how the driver + manages memory. Pre-GEM drivers will use <function>drm_mmap</function>, + while GEM-aware drivers will use <function>drm_gem_mmap</function>. See + <xref linkend="drm-gem"/>. + <programlisting> + .mmap = drm_gem_mmap, + </programlisting> + </para> + <para> + No other file operation is supported by the DRM API. + </para> + </sect2> + <sect2> + <title>IOCTLs</title> + <synopsis>struct drm_ioctl_desc *ioctls; +int num_ioctls;</synopsis> + <abstract>Driver-specific ioctls descriptors table.</abstract> + <para> + Driver-specific ioctls numbers start at DRM_COMMAND_BASE. The ioctls + descriptors table is indexed by the ioctl number offset from the base + value. Drivers can use the DRM_IOCTL_DEF_DRV() macro to initialize the + table entries. + </para> + <para> + <programlisting>DRM_IOCTL_DEF_DRV(ioctl, func, flags)</programlisting> + <para> + <parameter>ioctl</parameter> is the ioctl name. Drivers must define + the DRM_##ioctl and DRM_IOCTL_##ioctl macros to the ioctl number + offset from DRM_COMMAND_BASE and the ioctl number respectively. The + first macro is private to the device while the second must be exposed + to userspace in a public header. + </para> + <para> + <parameter>func</parameter> is a pointer to the ioctl handler function + compatible with the <type>drm_ioctl_t</type> type. + <programlisting>typedef int drm_ioctl_t(struct drm_device *dev, void *data, + struct drm_file *file_priv);</programlisting> + </para> + <para> + <parameter>flags</parameter> is a bitmask combination of the following + values. It restricts how the ioctl is allowed to be called. + <itemizedlist> + <listitem><para> + DRM_AUTH - Only authenticated callers allowed + </para></listitem> + <listitem><para> + DRM_MASTER - The ioctl can only be called on the master file + handle + </para></listitem> + <listitem><para> + DRM_ROOT_ONLY - Only callers with the SYSADMIN capability allowed + </para></listitem> + <listitem><para> + DRM_CONTROL_ALLOW - The ioctl can only be called on a control + device + </para></listitem> + <listitem><para> + DRM_UNLOCKED - The ioctl handler will be called without locking + the DRM global mutex + </para></listitem> + </itemizedlist> + </para> + </para> + </sect2> + </sect1> + <sect1> + <title>Legacy Support Code</title> + <para> + The section very briefly covers some of the old legacy support code which + is only used by old DRM drivers which have done a so-called shadow-attach + to the underlying device instead of registering as a real driver. This + also includes some of the old generic buffer management and command + submission code. Do not use any of this in new and modern drivers. + </para> + + <sect2> + <title>Legacy Suspend/Resume</title> + <para> + The DRM core provides some suspend/resume code, but drivers wanting full + suspend/resume support should provide save() and restore() functions. + These are called at suspend, hibernate, or resume time, and should perform + any state save or restore required by your device across suspend or + hibernate states. + </para> + <synopsis>int (*suspend) (struct drm_device *, pm_message_t state); + int (*resume) (struct drm_device *);</synopsis> + <para> + Those are legacy suspend and resume methods which + <emphasis>only</emphasis> work with the legacy shadow-attach driver + registration functions. New driver should use the power management + interface provided by their bus type (usually through + the struct <structname>device_driver</structname> dev_pm_ops) and set + these methods to NULL. + </para> + </sect2> + + <sect2> + <title>Legacy DMA Services</title> + <para> + This should cover how DMA mapping etc. is supported by the core. + These functions are deprecated and should not be used. + </para> + </sect2> + </sect1> + </chapter> + +<!-- TODO + +- Add a glossary +- Document the struct_mutex catch-all lock +- Document connector properties + +- Why is the load method optional? +- What are drivers supposed to set the initial display state to, and how? + Connector's DPMS states are not initialized and are thus equal to + DRM_MODE_DPMS_ON. The fbcon compatibility layer calls + drm_helper_disable_unused_functions(), which disables unused encoders and + CRTCs, but doesn't touch the connectors' DPMS state, and + drm_helper_connector_dpms() in reaction to fbdev blanking events. Do drivers + that don't implement (or just don't use) fbcon compatibility need to call + those functions themselves? +- vblank_disable_allowed is set to 1 in the first drm_vblank_post_modeset() + call and never set back to 0. It seems to be safe to permanently set it to 1 + in drm_vblank_init() for KMS driver, and it might be safe for UMS drivers as + well. This should be investigated. +- crtc and connector .save and .restore operations are only used internally in + drivers, should they be removed from the core? +- encoder mid-layer .save and .restore operations are only used internally in + drivers, should they be removed from the core? +- encoder mid-layer .detect operation is only used internally in drivers, + should it be removed from the core? +--> + + <!-- External interfaces --> + + <chapter id="drmExternals"> + <title>Userland interfaces</title> + <para> + The DRM core exports several interfaces to applications, + generally intended to be used through corresponding libdrm + wrapper functions. In addition, drivers export device-specific + interfaces for use by userspace drivers &amp; device-aware + applications through ioctls and sysfs files. + </para> + <para> + External interfaces include: memory mapping, context management, + DMA operations, AGP management, vblank control, fence + management, memory management, and output management. + </para> + <para> + Cover generic ioctls and sysfs layout here. We only need high-level + info, since man pages should cover the rest. + </para> + + <!-- External: render nodes --> + + <sect1> + <title>Render nodes</title> + <para> + DRM core provides multiple character-devices for user-space to use. + Depending on which device is opened, user-space can perform a different + set of operations (mainly ioctls). The primary node is always created + and called card&lt;num&gt;. Additionally, a currently + unused control node, called controlD&lt;num&gt; is also + created. The primary node provides all legacy operations and + historically was the only interface used by userspace. With KMS, the + control node was introduced. However, the planned KMS control interface + has never been written and so the control node stays unused to date. + </para> + <para> + With the increased use of offscreen renderers and GPGPU applications, + clients no longer require running compositors or graphics servers to + make use of a GPU. But the DRM API required unprivileged clients to + authenticate to a DRM-Master prior to getting GPU access. To avoid this + step and to grant clients GPU access without authenticating, render + nodes were introduced. Render nodes solely serve render clients, that + is, no modesetting or privileged ioctls can be issued on render nodes. + Only non-global rendering commands are allowed. If a driver supports + render nodes, it must advertise it via the DRIVER_RENDER + DRM driver capability. If not supported, the primary node must be used + for render clients together with the legacy drmAuth authentication + procedure. + </para> + <para> + If a driver advertises render node support, DRM core will create a + separate render node called renderD&lt;num&gt;. There will + be one render node per device. No ioctls except PRIME-related ioctls + will be allowed on this node. Especially GEM_OPEN will be + explicitly prohibited. Render nodes are designed to avoid the + buffer-leaks, which occur if clients guess the flink names or mmap + offsets on the legacy interface. Additionally to this basic interface, + drivers must mark their driver-dependent render-only ioctls as + DRM_RENDER_ALLOW so render clients can use them. Driver + authors must be careful not to allow any privileged ioctls on render + nodes. + </para> + <para> + With render nodes, user-space can now control access to the render node + via basic file-system access-modes. A running graphics server which + authenticates clients on the privileged primary/legacy node is no longer + required. Instead, a client can open the render node and is immediately + granted GPU access. Communication between clients (or servers) is done + via PRIME. FLINK from render node to legacy node is not supported. New + clients must not use the insecure FLINK interface. + </para> + <para> + Besides dropping all modeset/global ioctls, render nodes also drop the + DRM-Master concept. There is no reason to associate render clients with + a DRM-Master as they are independent of any graphics server. Besides, + they must work without any running master, anyway. + Drivers must be able to run without a master object if they support + render nodes. If, on the other hand, a driver requires shared state + between clients which is visible to user-space and accessible beyond + open-file boundaries, they cannot support render nodes. + </para> + </sect1> + + <!-- External: vblank handling --> + + <sect1> + <title>VBlank event handling</title> + <para> + The DRM core exposes two vertical blank related ioctls: + <variablelist> + <varlistentry> + <term>DRM_IOCTL_WAIT_VBLANK</term> + <listitem> + <para> + This takes a struct drm_wait_vblank structure as its argument, + and it is used to block or request a signal when a specified + vblank event occurs. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term>DRM_IOCTL_MODESET_CTL</term> + <listitem> + <para> + This was only used for user-mode-settind drivers around + modesetting changes to allow the kernel to update the vblank + interrupt after mode setting, since on many devices the vertical + blank counter is reset to 0 at some point during modeset. Modern + drivers should not call this any more since with kernel mode + setting it is a no-op. + </para> + </listitem> + </varlistentry> + </variablelist> + </para> + </sect1> + + </chapter> +</part> +<part id="drmDrivers"> + <title>DRM Drivers</title> + + <partintro> + <para> + This second part of the DRM Developer's Guide documents driver code, + implementation details and also all the driver-specific userspace + interfaces. Especially since all hardware-acceleration interfaces to + userspace are driver specific for efficiency and other reasons these + interfaces can be rather substantial. Hence every driver has its own + chapter. + </para> + </partintro> + + <chapter id="drmI915"> + <title>drm/i915 Intel GFX Driver</title> + <para> + The drm/i915 driver supports all (with the exception of some very early + models) integrated GFX chipsets with both Intel display and rendering + blocks. This excludes a set of SoC platforms with an SGX rendering unit, + those have basic support through the gma500 drm driver. + </para> + <sect1> + <title>Core Driver Infrastructure</title> + <para> + This section covers core driver infrastructure used by both the display + and the GEM parts of the driver. + </para> + <sect2> + <title>Runtime Power Management</title> +!Pdrivers/gpu/drm/i915/intel_runtime_pm.c runtime pm +!Idrivers/gpu/drm/i915/intel_runtime_pm.c +!Idrivers/gpu/drm/i915/intel_uncore.c + </sect2> + <sect2> + <title>Interrupt Handling</title> +!Pdrivers/gpu/drm/i915/i915_irq.c interrupt handling +!Fdrivers/gpu/drm/i915/i915_irq.c intel_irq_init intel_irq_init_hw intel_hpd_init +!Fdrivers/gpu/drm/i915/i915_irq.c intel_runtime_pm_disable_interrupts +!Fdrivers/gpu/drm/i915/i915_irq.c intel_runtime_pm_enable_interrupts + </sect2> + <sect2> + <title>Intel GVT-g Guest Support(vGPU)</title> +!Pdrivers/gpu/drm/i915/i915_vgpu.c Intel GVT-g guest support +!Idrivers/gpu/drm/i915/i915_vgpu.c + </sect2> + </sect1> + <sect1> + <title>Display Hardware Handling</title> + <para> + This section covers everything related to the display hardware including + the mode setting infrastructure, plane, sprite and cursor handling and + display, output probing and related topics. + </para> + <sect2> + <title>Mode Setting Infrastructure</title> + <para> + The i915 driver is thus far the only DRM driver which doesn't use the + common DRM helper code to implement mode setting sequences. Thus it + has its own tailor-made infrastructure for executing a display + configuration change. + </para> + </sect2> + <sect2> + <title>Frontbuffer Tracking</title> +!Pdrivers/gpu/drm/i915/intel_frontbuffer.c frontbuffer tracking +!Idrivers/gpu/drm/i915/intel_frontbuffer.c +!Fdrivers/gpu/drm/i915/i915_gem.c i915_gem_track_fb + </sect2> + <sect2> + <title>Display FIFO Underrun Reporting</title> +!Pdrivers/gpu/drm/i915/intel_fifo_underrun.c fifo underrun handling +!Idrivers/gpu/drm/i915/intel_fifo_underrun.c + </sect2> + <sect2> + <title>Plane Configuration</title> + <para> + This section covers plane configuration and composition with the + primary plane, sprites, cursors and overlays. This includes the + infrastructure to do atomic vsync'ed updates of all this state and + also tightly coupled topics like watermark setup and computation, + framebuffer compression and panel self refresh. + </para> + </sect2> + <sect2> + <title>Atomic Plane Helpers</title> +!Pdrivers/gpu/drm/i915/intel_atomic_plane.c atomic plane helpers +!Idrivers/gpu/drm/i915/intel_atomic_plane.c + </sect2> + <sect2> + <title>Output Probing</title> + <para> + This section covers output probing and related infrastructure like the + hotplug interrupt storm detection and mitigation code. Note that the + i915 driver still uses most of the common DRM helper code for output + probing, so those sections fully apply. + </para> + </sect2> + <sect2> + <title>Hotplug</title> +!Pdrivers/gpu/drm/i915/intel_hotplug.c Hotplug +!Idrivers/gpu/drm/i915/intel_hotplug.c + </sect2> + <sect2> + <title>High Definition Audio</title> +!Pdrivers/gpu/drm/i915/intel_audio.c High Definition Audio over HDMI and Display Port +!Idrivers/gpu/drm/i915/intel_audio.c + </sect2> + <sect2> + <title>Panel Self Refresh PSR (PSR/SRD)</title> +!Pdrivers/gpu/drm/i915/intel_psr.c Panel Self Refresh (PSR/SRD) +!Idrivers/gpu/drm/i915/intel_psr.c + </sect2> + <sect2> + <title>Frame Buffer Compression (FBC)</title> +!Pdrivers/gpu/drm/i915/intel_fbc.c Frame Buffer Compression (FBC) +!Idrivers/gpu/drm/i915/intel_fbc.c + </sect2> + <sect2> + <title>Display Refresh Rate Switching (DRRS)</title> +!Pdrivers/gpu/drm/i915/intel_dp.c Display Refresh Rate Switching (DRRS) +!Fdrivers/gpu/drm/i915/intel_dp.c intel_dp_set_drrs_state +!Fdrivers/gpu/drm/i915/intel_dp.c intel_edp_drrs_enable +!Fdrivers/gpu/drm/i915/intel_dp.c intel_edp_drrs_disable +!Fdrivers/gpu/drm/i915/intel_dp.c intel_edp_drrs_invalidate +!Fdrivers/gpu/drm/i915/intel_dp.c intel_edp_drrs_flush +!Fdrivers/gpu/drm/i915/intel_dp.c intel_dp_drrs_init + + </sect2> + <sect2> + <title>DPIO</title> +!Pdrivers/gpu/drm/i915/i915_reg.h DPIO + </sect2> + + <sect2> + <title>CSR firmware support for DMC</title> +!Pdrivers/gpu/drm/i915/intel_csr.c csr support for dmc +!Idrivers/gpu/drm/i915/intel_csr.c + </sect2> + </sect1> + + <sect1> + <title>Memory Management and Command Submission</title> + <para> + This sections covers all things related to the GEM implementation in the + i915 driver. + </para> + <sect2> + <title>Batchbuffer Parsing</title> +!Pdrivers/gpu/drm/i915/i915_cmd_parser.c batch buffer command parser +!Idrivers/gpu/drm/i915/i915_cmd_parser.c + </sect2> + <sect2> + <title>Batchbuffer Pools</title> +!Pdrivers/gpu/drm/i915/i915_gem_batch_pool.c batch pool +!Idrivers/gpu/drm/i915/i915_gem_batch_pool.c + </sect2> + <sect2> + <title>Logical Rings, Logical Ring Contexts and Execlists</title> +!Pdrivers/gpu/drm/i915/intel_lrc.c Logical Rings, Logical Ring Contexts and Execlists +!Idrivers/gpu/drm/i915/intel_lrc.c + </sect2> + <sect2> + <title>Global GTT views</title> +!Pdrivers/gpu/drm/i915/i915_gem_gtt.c Global GTT views +!Idrivers/gpu/drm/i915/i915_gem_gtt.c + </sect2> + <sect2> + <title>GTT Fences and Swizzling</title> +!Idrivers/gpu/drm/i915/i915_gem_fence.c + <sect3> + <title>Global GTT Fence Handling</title> +!Pdrivers/gpu/drm/i915/i915_gem_fence.c fence register handling + </sect3> + <sect3> + <title>Hardware Tiling and Swizzling Details</title> +!Pdrivers/gpu/drm/i915/i915_gem_fence.c tiling swizzling details + </sect3> + </sect2> + <sect2> + <title>Object Tiling IOCTLs</title> +!Idrivers/gpu/drm/i915/i915_gem_tiling.c +!Pdrivers/gpu/drm/i915/i915_gem_tiling.c buffer object tiling + </sect2> + <sect2> + <title>Buffer Object Eviction</title> + <para> + This section documents the interface functions for evicting buffer + objects to make space available in the virtual gpu address spaces. + Note that this is mostly orthogonal to shrinking buffer objects + caches, which has the goal to make main memory (shared with the gpu + through the unified memory architecture) available. + </para> +!Idrivers/gpu/drm/i915/i915_gem_evict.c + </sect2> + <sect2> + <title>Buffer Object Memory Shrinking</title> + <para> + This section documents the interface function for shrinking memory + usage of buffer object caches. Shrinking is used to make main memory + available. Note that this is mostly orthogonal to evicting buffer + objects, which has the goal to make space in gpu virtual address + spaces. + </para> +!Idrivers/gpu/drm/i915/i915_gem_shrinker.c + </sect2> + </sect1> + <sect1> + <title>GuC-based Command Submission</title> + <sect2> + <title>GuC</title> +!Pdrivers/gpu/drm/i915/intel_guc_loader.c GuC-specific firmware loader +!Idrivers/gpu/drm/i915/intel_guc_loader.c + </sect2> + <sect2> + <title>GuC Client</title> +!Pdrivers/gpu/drm/i915/i915_guc_submission.c GuC-based command submissison +!Idrivers/gpu/drm/i915/i915_guc_submission.c + </sect2> + </sect1> + + <sect1> + <title> Tracing </title> + <para> + This sections covers all things related to the tracepoints implemented in + the i915 driver. + </para> + <sect2> + <title> i915_ppgtt_create and i915_ppgtt_release </title> +!Pdrivers/gpu/drm/i915/i915_trace.h i915_ppgtt_create and i915_ppgtt_release tracepoints + </sect2> + <sect2> + <title> i915_context_create and i915_context_free </title> +!Pdrivers/gpu/drm/i915/i915_trace.h i915_context_create and i915_context_free tracepoints + </sect2> + <sect2> + <title> switch_mm </title> +!Pdrivers/gpu/drm/i915/i915_trace.h switch_mm tracepoint + </sect2> + </sect1> + + </chapter> +!Cdrivers/gpu/drm/i915/i915_irq.c +</part> +</book>

Following Daniel's renaming of the document.

Signed-off-by: Lukas Wunner lukas@wunner.de --- Documentation/DocBook/gpu.tmpl | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/Documentation/DocBook/gpu.tmpl b/Documentation/DocBook/gpu.tmpl index 94c600c..e506c70 100644 --- a/Documentation/DocBook/gpu.tmpl +++ b/Documentation/DocBook/gpu.tmpl @@ -2,7 +2,7 @@ <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []>

-<book id="drmDevelopersGuide"> +<book id="gpuDevelopersGuide"> <bookinfo> <title>Linux GPU Driver Developer's Guide</title>

@@ -78,9 +78,9 @@ <title>DRM Core</title> <partintro> <para> - This first part of the DRM Developer's Guide documents core DRM code, - helper libraries for writing drivers and generic userspace interfaces - exposed by DRM drivers. + This first part of the GPU Driver Developer's Guide documents core DRM + code, helper libraries for writing drivers and generic userspace + interfaces exposed by DRM drivers. </para> </partintro>

@@ -3947,8 +3947,8 @@ int num_ioctls;</synopsis>

<partintro> <para> - This second part of the DRM Developer's Guide documents driver code, - implementation details and also all the driver-specific userspace + This second part of the GPU Driver Developer's Guide documents driver + code, implementation details and also all the driver-specific userspace interfaces. Especially since all hardware-acceleration interfaces to userspace are driver specific for efficiency and other reasons these interfaces can be rather substantial. Hence every driver has its own

This snippet...

* Lock VMA manager for extended lookups. Only *_locked() VMA function calls * are allowed while holding this lock. All other contexts are blocked from VMA * until the lock is released via drm_vma_offset_unlock_lookup().

...causes markdown-enabled kernel-doc to barf:

debian/build/build-doc/Documentation/DocBook/gpu.aux.xml:3247: parser error : Opening and ending tag mismatch: emphasis line 3247 and function *<function><emphasis>locked</function> VMA function calls are allowed while ^ /root/airlied/debian/build/build-doc/Documentation/DocBook/gpu.aux.xml:3249: parser error : Opening and ending tag mismatch: function line 3249 and emphasis released via <function>drm</emphasis>vma_offset_unlock_lookup</function>. ^ unable to parse /root/airlied/debian/build/build-doc/Documentation/DocBook/gpu.aux.xml

A quick workaround is to replace *_locked() by X_locked().

Cc: Danilo Cesar Lemes de Paula danilo.cesar@collabora.co.uk Signed-off-by: Lukas Wunner lukas@wunner.de --- include/drm/drm_vma_manager.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/drm/drm_vma_manager.h b/include/drm/drm_vma_manager.h index 2ca44db..c1e41b8 100644 --- a/include/drm/drm_vma_manager.h +++ b/include/drm/drm_vma_manager.h @@ -97,7 +97,7 @@ drm_vma_offset_exact_lookup(struct drm_vma_offset_manager *mgr, * drm_vma_offset_lock_lookup() - Lock lookup for extended private use * @mgr: Manager object * - * Lock VMA manager for extended lookups. Only *_locked() VMA function calls + * Lock VMA manager for extended lookups. Only X_locked() VMA function calls * are allowed while holding this lock. All other contexts are blocked from VMA * until the lock is released via drm_vma_offset_unlock_lookup(). *

On 10/14/2015 10:59 AM, Daniel Vetter wrote:

On Mon, Oct 12, 2015 at 09:10:33AM +0200, Lukas Wunner wrote:

...

This snippet...

* Lock VMA manager for extended lookups. Only *_locked() VMA function calls
* are allowed while holding this lock. All other contexts are blocked from VMA
* until the lock is released via drm_vma_offset_unlock_lookup().

...causes markdown-enabled kernel-doc to barf:

debian/build/build-doc/Documentation/DocBook/gpu.aux.xml:3247: parser error : Opening and ending tag mismatch: emphasis line 3247 and function
   *<function><emphasis>locked</function> VMA function calls are allowed while
                                         ^
/root/airlied/debian/build/build-doc/Documentation/DocBook/gpu.aux.xml:3249: parser error : Opening and ending tag mismatch: function line 3249 and emphasis
   released via <function>drm</emphasis>vma_offset_unlock_lookup</function>.
                                        ^
unable to parse /root/airlied/debian/build/build-doc/Documentation/DocBook/gpu.aux.xml

A quick workaround is to replace *_locked() by X_locked().

Cc: Danilo Cesar Lemes de Paula danilo.cesar@collabora.co.uk Signed-off-by: Lukas Wunner lukas@wunner.de

---

include/drm/drm_vma_manager.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/drm/drm_vma_manager.h b/include/drm/drm_vma_manager.h index 2ca44db..c1e41b8 100644 --- a/include/drm/drm_vma_manager.h +++ b/include/drm/drm_vma_manager.h @@ -97,7 +97,7 @@ drm_vma_offset_exact_lookup(struct drm_vma_offset_manager *mgr,

• drm_vma_offset_lock_lookup() - Lock lookup for extended private use
• @mgr: Manager object

• • Lock VMA manager for extended lookups. Only *_locked() VMA function calls

• • Lock VMA manager for extended lookups. Only X_locked() VMA function calls

I went with a plain _unlocked since the X_unlocked looked a bit strange. Anyway Dave acked the rename idea on irc, so all applied. Well except patch 1, there wasn't any conflict when I pushed this to drm-misc. -Daniel

I didn't test it (not a big fan of doing this), but * or _ should escape the sequence. Did you consider that?

Danilo

...

• are allowed while holding this lock. All other contexts are blocked from VMA
• until the lock is released via drm_vma_offset_unlock_lookup().

-- 1.8.5.2 (Apple Git-48)

On Wed, Oct 14, 2015 at 05:54:31PM +0200, Lukas Wunner wrote:

Hi,

On Wed, Oct 14, 2015 at 11:04:37AM -0300, Danilo Cesar Lemes de Paula wrote:

...

On 10/14/2015 10:59 AM, Daniel Vetter wrote:

...

On Mon, Oct 12, 2015 at 09:10:33AM +0200, Lukas Wunner wrote:

...

This snippet...

* Lock VMA manager for extended lookups. Only *_locked() VMA function calls
* are allowed while holding this lock. All other contexts are blocked from VMA
* until the lock is released via drm_vma_offset_unlock_lookup().

...causes markdown-enabled kernel-doc to barf:

debian/build/build-doc/Documentation/DocBook/gpu.aux.xml:3247: parser error : Opening and ending tag mismatch: emphasis line 3247 and function
   *<function><emphasis>locked</function> VMA function calls are allowed while
                                         ^
/root/airlied/debian/build/build-doc/Documentation/DocBook/gpu.aux.xml:3249: parser error : Opening and ending tag mismatch: function line 3249 and emphasis
   released via <function>drm</emphasis>vma_offset_unlock_lookup</function>.
                                        ^
unable to parse /root/airlied/debian/build/build-doc/Documentation/DocBook/gpu.aux.xml

A quick workaround is to replace *_locked() by X_locked().

Cc: Danilo Cesar Lemes de Paula danilo.cesar@collabora.co.uk Signed-off-by: Lukas Wunner lukas@wunner.de

---

include/drm/drm_vma_manager.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/drm/drm_vma_manager.h b/include/drm/drm_vma_manager.h index 2ca44db..c1e41b8 100644 --- a/include/drm/drm_vma_manager.h +++ b/include/drm/drm_vma_manager.h @@ -97,7 +97,7 @@ drm_vma_offset_exact_lookup(struct drm_vma_offset_manager *mgr,

• drm_vma_offset_lock_lookup() - Lock lookup for extended private use
• @mgr: Manager object

• • Lock VMA manager for extended lookups. Only *_locked() VMA function calls

• • Lock VMA manager for extended lookups. Only X_locked() VMA function calls

I went with a plain _unlocked since the X_unlocked looked a bit strange. Anyway Dave acked the rename idea on irc, so all applied. Well except patch 1, there wasn't any conflict when I pushed this to drm-misc. -Daniel

I didn't test it (not a big fan of doing this), but * or _ should escape the sequence. Did you consider that?

I did test * and it didn't help. I can't remember if I also tested _.

In any case the issue is not the asterisk but rather that the underscore in *_locked() is interpreted as the beginning of an _emphasis_. It seems any underscore at the beginning of a word is interpreted like that. The question is why the leading asterisk is not interpreted as the actual beginning of the word. Replacing the asterisk with an alphabetic character solved it.

Ok, missed that, so now we have just "locked" instead of "_locked()". -Daniel