VBLANK_END_MASK
vblank_end = REG_FIELD_GET(VBLANK_END_MASK, vblank) + 1;
adjusted_mode->crtc_vblank_end = REG_FIELD_GET(VBLANK_END_MASK, tmp) + 1;
#define VBLANK_END(vblank_end) REG_FIELD_PREP(VBLANK_END_MASK, (vblank_end))