2 files changed, 23 insertions, 5 deletions

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 11d7a72c22d9..140b9525b48a 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -1516,17 +1516,33 @@ bool drm_fb_helper_initial_config(struct drm_fb_helper *fb_helper, int bpp_sel)
 }
 EXPORT_SYMBOL(drm_fb_helper_initial_config);
 
-bool drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper)
+/**
+ * drm_fb_helper_hotplug_event - respond to a hotplug notification by
+ *                               probing all the outputs attached to the fb.
+ * @fb_helper: the drm_fb_helper
+ *
+ * LOCKING:
+ * Called at runtime, must take mode config lock.
+ *
+ * Scan the connectors attached to the fb_helper and try to put together a
+ * setup after *notification of a change in output configuration.
+ *
+ * RETURNS:
+ * 0 on success and a non-zero error code otherwise.
+ */
+int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper)
 {
+        struct drm_device *dev = fb_helper->dev;
         int count = 0;
         u32 max_width, max_height, bpp_sel;
         bool bound = false, crtcs_bound = false;
         struct drm_crtc *crtc;
 
         if (!fb_helper->fb)
-                return false;
+                return 0;
 
-        list_for_each_entry(crtc, &fb_helper->dev->mode_config.crtc_list, head) {
+        mutex_lock(&dev->mode_config.mutex);
+        list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
                 if (crtc->fb)
                         crtcs_bound = true;
                 if (crtc->fb == fb_helper->fb)
@@ -1535,7 +1551,8 @@ bool drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper)
 
         if (!bound && crtcs_bound) {
                 fb_helper->delayed_hotplug = true;
-                return false;
+                mutex_unlock(&dev->mode_config.mutex);
+                return 0;
         }
         DRM_DEBUG_KMS("\n");
 
@@ -1546,6 +1563,7 @@ bool drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper)
         count = drm_fb_helper_probe_connector_modes(fb_helper, max_width,
                                                     max_height);
         drm_setup_crtcs(fb_helper);
+        mutex_unlock(&dev->mode_config.mutex);
 
         return drm_fb_helper_single_fb_probe(fb_helper, bpp_sel);
 }
diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h
index ade09d7b4271..c99c3d3e7811 100644
--- a/include/drm/drm_fb_helper.h
+++ b/include/drm/drm_fb_helper.h
@@ -127,7 +127,7 @@ void drm_fb_helper_fill_fix(struct fb_info *info, uint32_t pitch,
 
 int drm_fb_helper_setcmap(struct fb_cmap *cmap, struct fb_info *info);
 
-bool drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper);
+int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper);
 bool drm_fb_helper_initial_config(struct drm_fb_helper *fb_helper, int bpp_sel);
 int drm_fb_helper_single_add_all_connectors(struct drm_fb_helper *fb_helper);
 int drm_fb_helper_debug_enter(struct fb_info *info);