mmALPHA_CONTROL
tmp = RREG32(mmALPHA_CONTROL + amdgpu_crtc->crtc_offset);
WREG32(mmALPHA_CONTROL + amdgpu_crtc->crtc_offset, tmp);
WREG32(mmALPHA_CONTROL + amdgpu_crtc->crtc_offset,