drm/atomic: add commit_planes_on_crtc helper

[Dan Carpenter]

Hello Maarten Lankhorst,

This is a semi-automatic email about new static checker warnings.

The patch 32975e952e85: "drm/atomic: add commit_planes_on_crtc 
helper" from May 19, 2015, leads to the following Smatch complaint:

drivers/gpu/drm/drm_atomic_helper.c:1244 drm_atomic_helper_commit_planes_on_crtc()
	 error: we previously assumed 'crtc_funcs' could be null (see line 1221)

drivers/gpu/drm/drm_atomic_helper.c
  1220		crtc_funcs = crtc->helper_private;
  1221		if (crtc_funcs && crtc_funcs->atomic_begin)
                    ^^^^^^^^^^
Check.

  1222			crtc_funcs->atomic_begin(crtc);
  1223	
  1224		drm_for_each_plane_mask(plane, crtc->dev, plane_mask) {
  1225			struct drm_plane_state *old_plane_state =
  1226				drm_atomic_get_existing_plane_state(old_state, plane);
  1227			const struct drm_plane_helper_funcs *plane_funcs;
  1228	
  1229			plane_funcs = plane->helper_private;
  1230	
  1231			if (!old_plane_state || !plane_funcs)
  1232				continue;
  1233	
  1234			WARN_ON(plane->state->crtc && plane->state->crtc != crtc);
  1235	
  1236			if (drm_atomic_plane_disabling(plane, old_plane_state) &&
  1237			    plane_funcs->atomic_disable)
  1238				plane_funcs->atomic_disable(plane, old_plane_state);
  1239			else if (plane->state->crtc ||
  1240				 drm_atomic_plane_disabling(plane, old_plane_state))
  1241				plane_funcs->atomic_update(plane, old_plane_state);
  1242		}
  1243	
  1244		if (crtc_funcs->atomic_flush)
                    ^^^^^^^^^^
Unchecked dereference.

  1245			crtc_funcs->atomic_flush(crtc);
  1246	}

regards,
dan carpenter