BackMerge v5.1-rc5 into drm-next

Need rc5 for udl fix to add udl cleanups on top.

Signed-off-by: Dave Airlie <airlied@redhat.com>

include/drm/drm_modeset_helper_vtables.h

@@ -420,6 +420,8 @@ struct drm_crtc_helper_funcs {
 	 * Drivers can use the @old_crtc_state input parameter if the operations
 	 * needed to enable the CRTC don't depend solely on the new state but
 	 * also on the transition between the old state and the new state.
+	 *
+	 * This function is optional.
 	 */
 	void (*atomic_enable)(struct drm_crtc *crtc,
 			      struct drm_crtc_state *old_crtc_state);
@@ -443,6 +445,8 @@ struct drm_crtc_helper_funcs {
 	 * parameter @old_crtc_state which could be used to access the old
 	 * state. Atomic drivers should consider to use this one instead
 	 * of @disable.
+	 *
+	 * This function is optional.
 	 */
 	void (*atomic_disable)(struct drm_crtc *crtc,
 			       struct drm_crtc_state *old_crtc_state);