drm/bridge: Document bridge init order with pre_enable_prev_first

In order to satisfy the MIPI DSI initialization sequence the bridge
init order has been altered with the help of pre_enable_prev_first
in pre_enable and post_disable bridge operations.

Document the affected bridge init order with an example on the
bridge operations helpers.

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Robert Foss <rfoss@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230328170752.1102347-2-jagan@amarulasolutions.com

diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index 17ed94885dc3b485cf7f10c3a8a5c980f9ac5cfe..28abe9aa99ca574ab77804ff82435784841d7383 100644 (file)
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -657,6 +657,13 @@ static void drm_atomic_bridge_call_post_disable(struct drm_bridge *bridge,
  * bridge will be called before the previous one to reverse the @pre_enable
  * calling direction.
  *
+ * Example:
+ * Bridge A ---> Bridge B ---> Bridge C ---> Bridge D ---> Bridge E
+ *
+ * With pre_enable_prev_first flag enable in Bridge B, D, E then the resulting
+ * @post_disable order would be,
+ * Bridge B, Bridge A, Bridge E, Bridge D, Bridge C.
+ *
  * Note: the bridge passed should be the one closest to the encoder
  */
 void drm_atomic_bridge_chain_post_disable(struct drm_bridge *bridge,
@@ -753,6 +760,13 @@ static void drm_atomic_bridge_call_pre_enable(struct drm_bridge *bridge,
  * If a bridge sets @pre_enable_prev_first, then the pre_enable for the
  * prev bridge will be called before pre_enable of this bridge.
  *
+ * Example:
+ * Bridge A ---> Bridge B ---> Bridge C ---> Bridge D ---> Bridge E
+ *
+ * With pre_enable_prev_first flag enable in Bridge B, D, E then the resulting
+ * @pre_enable order would be,
+ * Bridge C, Bridge D, Bridge E, Bridge A, Bridge B.
+ *
  * Note: the bridge passed should be the one closest to the encoder
  */
 void drm_atomic_bridge_chain_pre_enable(struct drm_bridge *bridge,