drm/doc: integrate fb helper reference into docs

Again only minimal changes to make kerneldoc no longer shout. Plus a
little introduction in the form of a inline DOC: section to quickly
explain what this is all about.

v2: Fixup spelling fail.

Acked-by: Laurent Pinchart <[e-mail]>
Signed-off-by: Daniel Vetter <[e-mail]>
Signed-off-by: Dave Airlie <[e-mail]>

Documentation/DocBook/drm.tmpl

···
       <title>Modeset Helper Functions Reference</title>
 !Edrivers/gpu/drm/drm_crtc_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
+    </sect2>
   </sect1>
 
   <!-- Internals: vertical blanking -->

drivers/gpu/drm/drm_fb_helper.c

···
 
 static LIST_HEAD(kernel_fb_helper_list);
 
+/**
+ * DOC: fbdev helpers
+ *
+ * The fb helper functions are useful to provide an fbdev on top of a drm kernel
+ * mode setting driver. They can be used mostly independantely from the crtc
+ * helper functions used by many drivers to implement the kernel mode setting
+ * interfaces.
+ */
+
 /* simple single crtc case helper function */
 int drm_fb_helper_single_add_all_connectors(struct drm_fb_helper *fb_helper)
 {
···
 
 /**
  * drm_helper_initial_config - setup a sane initial connector configuration
- * @dev: DRM device
+ * @fb_helper: fb_helper device struct
+ * @bpp_sel: bpp value to use for the framebuffer configuration
  *
  * LOCKING:
- * Called at init time, must take mode config lock.
+ * Called at init time by the driver to set up the @fb_helper initial
+ * configuration, must take the mode config lock.
  *
- * Scan the CRTCs and connectors and try to put together an initial setup.
+ * Scans the CRTCs and connectors and tries to put together an initial setup.
  * At the moment, this is a cloned configuration across all heads with
  * a new framebuffer object as the backing store.
  *
···
 
 /**
  * drm_fb_helper_hotplug_event - respond to a hotplug notification by
- *                               probing all the outputs attached to the fb.
+ *                               probing all the outputs attached to the fb
  * @fb_helper: the drm_fb_helper
  *
  * LOCKING: