drm: Check for a NULL encoder when reverting on error path

We need to skip the connectors with a NULL encoder to match the success
path and avoid an OOPS.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Dave Airlie <airlied@linux.ie>

1 files changed, 5 insertions, 1 deletions

diff --git a/drivers/gpu/drm/drm_crtc_helper.c b/drivers/gpu/drm/drm_crtc_helper.c
index 964c5eb1fada..8ba22c039a11 100644
--- a/drivers/gpu/drm/drm_crtc_helper.c
+++ b/drivers/gpu/drm/drm_crtc_helper.c
@@ -775,8 +775,12 @@ int drm_crtc_helper_set_config(struct drm_mode_set *set)
 fail_set_mode:
         set->crtc->enabled = save_enabled;
         count = 0;
-        list_for_each_entry(connector, &dev->mode_config.connector_list, head)
+        list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
+                if (!connector->encoder)
+                        continue;
+
                 connector->encoder->crtc = save_crtcs[count++];
+        }
 fail_no_encoder:
         kfree(save_crtcs);
         count = 0;