_DRM_VBLANK_FLAGS_MASK
~(_DRM_VBLANK_TYPES_MASK | _DRM_VBLANK_FLAGS_MASK |
(_DRM_VBLANK_TYPES_MASK | _DRM_VBLANK_FLAGS_MASK |
flags = vblwait->request.type & _DRM_VBLANK_FLAGS_MASK;