drm/doc: Unify KMS Locking docs

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Acked-by: Jani Nikula <jani.nikula@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1464599449-12509-1-git-send-email-daniel.vetter@ffwll.ch

Documentation/DocBook/gpu.tmpl

@@ -1092,22 +1092,6 @@ int max_width, max_height;</synopsis>
         operation.
       </para>
     </sect2>
-    <sect2>
-      <title>Locking</title>
-      <para>
-        Beside some lookup structures with their own locking (which is hidden
-	behind the interface functions) most of the modeset state is protected
-	by the <code>dev-&lt;mode_config.lock</code> mutex and additionally
-	per-crtc locks to allow cursor updates, pageflips and similar operations
-	to occur concurrently with background tasks like output detection.
-	Operations which cross domains like a full modeset always grab all
-	locks. Drivers there need to protect resources shared between crtcs with
-	additional locking. They also need to be careful to always grab the
-	relevant crtc locks if a modset functions touches crtc state, e.g. for
-	load detection (which does only grab the <code>mode_config.lock</code>
-	to allow concurrent screen updates on live crtcs).
-      </para>
-    </sect2>
   </sect1>
 
   <!-- Internals: kms initialization and cleanup -->

drivers/gpu/drm/drm_modeset_lock.c

@@ -30,12 +30,12 @@
  *
  * As KMS moves toward more fine grained locking, and atomic ioctl where
  * userspace can indirectly control locking order, it becomes necessary
- * to use ww_mutex and acquire-contexts to avoid deadlocks.  But because
+ * to use &ww_mutex and acquire-contexts to avoid deadlocks.  But because
  * the locking is more distributed around the driver code, we want a bit
  * of extra utility/tracking out of our acquire-ctx.  This is provided
  * by drm_modeset_lock / drm_modeset_acquire_ctx.
  *
- * For basic principles of ww_mutex, see: Documentation/locking/ww-mutex-design.txt
+ * For basic principles of &ww_mutex, see: Documentation/locking/ww-mutex-design.txt
  *
  * The basic usage pattern is to:
  *
@@ -51,6 +51,13 @@
  *     ... do stuff ...
  *     drm_modeset_drop_locks(&ctx);
  *     drm_modeset_acquire_fini(&ctx);
+ *
+ *  On top of of these per-object locks using &ww_mutex there's also an overall
+ *  dev->mode_config.lock, for protecting everything else. Mostly this means
+ *  probe state of connectors, and preventing hotplug add/removal of connectors.
+ *
+ *  Finally there's a bunch of dedicated locks to protect drm core internal
+ *  lists and lookup data structures.
  */
 
 /**