* DRM_SCANOUTPOS_INVBL = Inside vblank.
* DRM_SCANOUTPOS_ACCURATE = Returned position is accurate. A lack of
* this flag means that returned position may be offset by a constant but
* DRM_SCANOUTPOS_INVBL = Inside vblank.
* DRM_SCANOUTPOS_ACCURATE = Returned position is accurate. A lack of
* this flag means that returned position may be offset by a constant but