Re: [PATCH v2 7/7] drm: Document how to register devices without struct drm_bus

Hi

On Tue, May 13, 2014 at 5:30 PM, Thierry Reding thierry.reding@gmail.com wrote:

From: Thierry Reding treding@nvidia.com

With the recent addition of the drm_set_unique() function, devices can now be registered without requiring a drm_bus. Add a brief description to the DRM docbook to show how that can be achieved.

Signed-off-by: Thierry Reding treding@nvidia.com

Documentation/DocBook/drm.tmpl | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+)

diff --git a/Documentation/DocBook/drm.tmpl b/Documentation/DocBook/drm.tmpl index f26a8e4fbe47..f48227caf41a 100644 --- a/Documentation/DocBook/drm.tmpl +++ b/Documentation/DocBook/drm.tmpl @@ -142,6 +142,12 @@ 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.

@@ -290,6 +296,29 @@ char *date;</synopsis> !Fdrivers/gpu/drm/drm_pci.c drm_pci_init drm_pci_exit !Fdrivers/gpu/drm/drm_usb.c drm_usb_init drm_usb_exit !Fdrivers/gpu/drm/drm_platform.c drm_platform_init

•  <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_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 using a
  

That's not true. drm_put_dev() is anything but safe.. but that's an implementation bug and I'm working on it. Not that easy, though. Furthermore, please use drm_dev_unregister() and drm_dev_unref() directly. No reason to use drm_put_dev() in new drivers. Once I fixed the runtime issues, a call to drm_dev_unregister() will _immediately_ remove a device and detach all active user-space connections.

•    call to <function>drm_put_dev()</function>.
  

•  </para>
  

+!Fdrivers/gpu/drm/drm_stub.c drm_dev_alloc

Please change this to:

+!Fdrivers/gpu/drm/drm_stub.c drm_dev_alloc +!Fdrivers/gpu/drm/drm_stub.c drm_dev_ref +!Fdrivers/gpu/drm/drm_stub.c drm_dev_unref +!Fdrivers/gpu/drm/drm_stub.c drm_dev_register +!Fdrivers/gpu/drm/drm_stub.c drm_dev_unregister +!Fdrivers/gpu/drm/drm_stub.c drm_dev_set_unique

All these helpers are needed and exported to drivers.

Otherwise, looks all good! Thanks! David

• </sect2> <sect2> <title>Driver Load</title> <para>

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