drm/fb-helper: document remove*_conflicting_framebuffers()

Copy remove*_conflicting_framebuffers() kerneldocs from fbdev code
to make DRM developers' life easier.
Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/f70c1cc4a4f77dd9bad58fc7ca344609c0a91fa7.1536342228.git.mirq-linux@rere.qmqm.pl

include/drm/drm_fb_helper.h

@@ -604,6 +604,16 @@ drm_fbdev_generic_setup(struct drm_device *dev, unsigned int preferred_bpp)
 
 #endif
 
+/**
+ * drm_fb_helper_remove_conflicting_framebuffers - remove firmware-configured framebuffers
+ * @a: memory range, users of which are to be removed
+ * @name: requesting driver name
+ * @primary: also kick vga16fb if present
+ *
+ * This function removes framebuffer devices (initialized by firmware/bootloader)
+ * which use memory range described by @a. If @a is NULL all such devices are
+ * removed.
+ */
 static inline int
 drm_fb_helper_remove_conflicting_framebuffers(struct apertures_struct *a,
 					      const char *name, bool primary)
@@ -615,6 +625,18 @@ drm_fb_helper_remove_conflicting_framebuffers(struct apertures_struct *a,
 #endif
 }
 
+/**
+ * drm_fb_helper_remove_conflicting_pci_framebuffers - remove firmware-configured framebuffers for PCI devices
+ * @pdev: PCI device
+ * @resource_id: index of PCI BAR configuring framebuffer memory
+ * @name: requesting driver name
+ *
+ * This function removes framebuffer devices (eg. initialized by firmware)
+ * using memory range configured for @pdev's BAR @resource_id.
+ *
+ * The function assumes that PCI device with shadowed ROM drives a primary
+ * display and so kicks out vga16fb.
+ */
 static inline int
 drm_fb_helper_remove_conflicting_pci_framebuffers(struct pci_dev *pdev,
 						  int resource_id,