drm: Add device registration documentation

Describe how devices are registered using the drm_*_init() functions.
Adding this to docbook requires a largish set of changes to the comments
in drm_{pci,usb,platform}.c since they are doxygen-style rather than
proper kernel-doc and therefore mess with the docbook generation.

While at it, mark usage of drm_put_dev() as discouraged in favour of
calling drm_dev_unregister() and drm_dev_unref() directly.

Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Thierry Reding <treding@nvidia.com>
diff --git a/drivers/gpu/drm/drm_platform.c b/drivers/gpu/drm/drm_platform.c
index 234e0bc..d5b76f1 100644
--- a/drivers/gpu/drm/drm_platform.c
+++ b/drivers/gpu/drm/drm_platform.c
@@ -106,17 +106,16 @@
 };
 
 /**
- * Platform device initialization. Called direct from modules.
+ * drm_platform_init - Register a platform device with the DRM subsystem
+ * @driver: DRM device driver
+ * @platform_device: platform device to register
  *
- * \return zero on success or a negative number on failure.
+ * Registers the specified DRM device driver and platform device with the DRM
+ * subsystem, initializing a drm_device structure and calling the driver's
+ * .load() function.
  *
- * Initializes a drm_device structures,registering the
- * stubs
- *
- * Expands the \c DRIVER_PREINIT and \c DRIVER_POST_INIT macros before and
- * after the initialization for driver customization.
+ * Return: 0 on success or a negative error code on failure.
  */
-
 int drm_platform_init(struct drm_driver *driver, struct platform_device *platform_device)
 {
 	DRM_DEBUG("\n");