drm: introduce atomic_begin for connector

atomic_begin is used to prepare for update flush.

Change-Id: I1d3a2afaea4022c065bda2b4c0746464cc0c1303
Signed-off-by: Zheng Yang <zhengyang@rock-chips.com>

Author: Zheng Yang

drivers/gpu/drm/drm_atomic_helper.c

@@ -1558,6 +1558,26 @@ void drm_atomic_helper_commit_planes(struct drm_device *dev,
 	struct drm_connector_state *old_conn_state;
 	int i;
 
+	for_each_connector_in_state(old_state, connector, old_conn_state, i) {
+		const struct drm_connector_helper_funcs *funcs;
+
+		if (!connector->state->crtc)
+			continue;
+
+		if (!connector->state->crtc->state->active)
+			continue;
+
+		funcs = connector->helper_private;
+
+		if (!funcs || !funcs->atomic_begin)
+			continue;
+
+		DRM_DEBUG_ATOMIC("flush beginning [CONNECTOR:%d:%s]\n",
+				 connector->base.id, connector->name);
+
+		funcs->atomic_begin(connector, old_conn_state);
+	}
+
 	for_each_crtc_in_state(old_state, crtc, old_crtc_state, i) {
 		const struct drm_crtc_helper_funcs *funcs;
 

include/drm/drm_crtc_helper.h

@@ -185,6 +185,8 @@ struct drm_connector_helper_funcs {
 	struct drm_encoder *(*best_encoder)(struct drm_connector *connector);
 	struct drm_encoder *(*atomic_best_encoder)(struct drm_connector *connector,
 						   struct drm_connector_state *connector_state);
+	void (*atomic_begin)(struct drm_connector *connector,
+			     struct drm_connector_state *conn_state);
 	void (*atomic_flush)(struct drm_connector *connector,
 			     struct drm_connector_state *conn_state);
 };