RADEON_FP_H2_SYNC_STRT_WID
WREG32(RADEON_FP_H2_SYNC_STRT_WID, RREG32(RADEON_CRTC2_H_SYNC_STRT_WID));
WREG32(RADEON_FP_H2_SYNC_STRT_WID, crtc_h_sync_strt_wid);