--- drivers/gpu/drm/udl/udl_drv.c.orig 2015-03-09 22:10:14.292335527 -0700 +++ drivers/gpu/drm/udl/udl_drv.c 2015-03-09 22:22:14.148342842 -0700 @@ -41,6 +41,7 @@ static struct drm_driver driver = { .load = udl_driver_load, .unload = udl_driver_unload, .set_busid = udl_driver_set_busid, + .get_vblank_counter = drm_vblank_count, /* gem hooks */ .gem_free_object = udl_gem_free_object,