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 & 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 & 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 - & 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 & 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->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->map_list.map</literal> being non-NULL. - </para> - <para> - Once allocated, the fake offset value - (<literal>obj->map_list.hash.key << 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<->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-<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->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->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->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 & 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->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->x</literal> and - <literal>crtc->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 & 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<num>. Additionally, a currently - unused control node, called controlD<num> 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<num>. 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 & 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 & 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 + & 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 & 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->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->map_list.map</literal> being non-NULL. + </para> + <para> + Once allocated, the fake offset value + (<literal>obj->map_list.hash.key << 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<->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-<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->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->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->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 & 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->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->x</literal> and + <literal>crtc->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 & 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<num>. Additionally, a currently + unused control node, called controlD<num> 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<num>. 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>