RADEON_CRTC_H_TOTAL_DISP
((RREG32(RADEON_CRTC_H_TOTAL_DISP) >> 16) + 1) * 8;
radeon_crtc->crtc_offset = RADEON_CRTC2_H_TOTAL_DISP - RADEON_CRTC_H_TOTAL_DISP;
WREG32(RADEON_CRTC_H_TOTAL_DISP + radeon_crtc->crtc_offset, crtc_h_total_disp);