drm: Don't try and disable an encoder that was never enabled

Prevents code that assumes that the encoder is active when asked to be
disabled from dying a horrible death.

Reported-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/gpu/drm/drm_crtc_helper.c b/drivers/gpu/drm/drm_crtc_helper.c
index 7ca59359fee2..bede10a03407 100644
--- a/drivers/gpu/drm/drm_crtc_helper.c
+++ b/drivers/gpu/drm/drm_crtc_helper.c
@@ -241,7 +241,7 @@ void drm_helper_disable_unused_functions(struct drm_device *dev)
         }
 
         list_for_each_entry(encoder, &dev->mode_config.encoder_list, head) {
-                if (!drm_helper_encoder_in_use(encoder)) {
+                if (encoder->crtc && !drm_helper_encoder_in_use(encoder)) {
                         drm_encoder_disable(encoder);
                         /* disconnector encoder from any connector */
                         encoder->crtc = NULL;