[PATCH] drm_atomic_helper: Copy/paste fix for calling already disabled planes

[Jasper St. Pierre]

This code was in drm_plane_helper, but missing from drm_atomic_helper,
causing various crashes when the plane was already disabled. Just copy
over the quick return there to prevent a crash.

Signed-off-by: Jasper St. Pierre <jstpierre at mecheye.net>
Reviewed-by: Rob Clark <robdclark at gmail.com>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
---
 drivers/gpu/drm/drm_atomic_helper.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index fad2b93..d96dac3 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -1246,6 +1246,11 @@ int drm_atomic_helper_disable_plane(struct drm_plane *plane)
 	struct drm_plane_state *plane_state;
 	int ret = 0;
 
+	/* crtc helpers love to call disable functions for already disabled hw
+	 * functions. So cope with that. */
+	if (!plane->crtc)
+		return 0;
+
 	state = drm_atomic_state_alloc(plane->dev);
 	if (!state)
 		return -ENOMEM;
-- 
2.1.0