drm: Document how to register devices without struct drm_bus
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.
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Thierry Reding <treding@nvidia.com>
diff --git a/Documentation/DocBook/drm.tmpl b/Documentation/DocBook/drm.tmpl
index ba09b6f..d95027f 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 +296,26 @@
!Edrivers/gpu/drm/drm_pci.c
!Edrivers/gpu/drm/drm_usb.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_stub.c
</sect2>
<sect2>
<title>Driver Load</title>