diff --git a/drivers/gpu/drm/drm_crtc_helper.c b/drivers/gpu/drm/drm_crtc_helper.c
index 5d2b7a5716e6..c0f2d6266070 100644
--- a/drivers/gpu/drm/drm_crtc_helper.c
+++ b/drivers/gpu/drm/drm_crtc_helper.c
@@ -983,6 +983,7 @@ void drm_helper_resume_force_mode(struct drm_device *dev)
 	int encoder_dpms;
 	bool ret;
 
+	drm_modeset_lock_all(dev);
 	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
 
 		if (!crtc->enabled)
@@ -1017,6 +1018,7 @@ void drm_helper_resume_force_mode(struct drm_device *dev)
 
 	/* disable the unused connectors while restoring the modesetting */
 	__drm_helper_disable_unused_functions(dev);
+	drm_modeset_unlock_all(dev);
 }
 EXPORT_SYMBOL(drm_helper_resume_force_mode);