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