1 files changed, 38 insertions, 2 deletions

diff --git a/drivers/gpu/drm/drm_crtc_helper.c b/drivers/gpu/drm/drm_crtc_helper.c
index 2957636161e..d2619d72cec 100644
--- a/drivers/gpu/drm/drm_crtc_helper.c
+++ b/drivers/gpu/drm/drm_crtc_helper.c
@@ -456,6 +456,30 @@ done:
 EXPORT_SYMBOL(drm_crtc_helper_set_mode);
 
 
+static int
+drm_crtc_helper_disable(struct drm_crtc *crtc)
+{
+        struct drm_device *dev = crtc->dev;
+        struct drm_connector *connector;
+        struct drm_encoder *encoder;
+
+        /* Decouple all encoders and their attached connectors from this crtc */
+        list_for_each_entry(encoder, &dev->mode_config.encoder_list, head) {
+                if (encoder->crtc != crtc)
+                        continue;
+
+                list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
+                        if (connector->encoder != encoder)
+                                continue;
+
+                        connector->encoder = NULL;
+                }
+        }
+
+        drm_helper_disable_unused_functions(dev);
+        return 0;
+}
+
 /**
  * drm_crtc_helper_set_config - set a new config from userspace
  * @crtc: CRTC to setup
@@ -484,6 +508,7 @@ int drm_crtc_helper_set_config(struct drm_mode_set *set)
         struct drm_connector *save_connectors, *connector;
         int count = 0, ro, fail = 0;
         struct drm_crtc_helper_funcs *crtc_funcs;
+        struct drm_mode_set save_set;
         int ret = 0;
         int i;
 
@@ -509,8 +534,7 @@ int drm_crtc_helper_set_config(struct drm_mode_set *set)
                                 (int)set->num_connectors, set->x, set->y);
         } else {
                 DRM_DEBUG_KMS("[CRTC:%d] [NOFB]\n", set->crtc->base.id);
-                set->mode = NULL;
-                set->num_connectors = 0;
+                return drm_crtc_helper_disable(set->crtc);
         }
 
         dev = set->crtc->dev;
@@ -556,6 +580,12 @@ int drm_crtc_helper_set_config(struct drm_mode_set *set)
                 save_connectors[count++] = *connector;
         }
 
+        save_set.crtc = set->crtc;
+        save_set.mode = &set->crtc->mode;
+        save_set.x = set->crtc->x;
+        save_set.y = set->crtc->y;
+        save_set.fb = set->crtc->fb;
+
         /* We should be able to check here if the fb has the same properties
          * and then just flip_or_move it */
         if (set->crtc->fb != set->fb) {
@@ -721,6 +751,12 @@ fail:
                 *connector = save_connectors[count++];
         }
 
+        /* Try to restore the config */
+        if (mode_changed &&
+            !drm_crtc_helper_set_mode(save_set.crtc, save_set.mode, save_set.x,
+                                      save_set.y, save_set.fb))
+                DRM_ERROR("failed to restore config after modeset failure\n");
+
         kfree(save_connectors);
         kfree(save_encoders);
         kfree(save_crtcs);