R700_MC_CITF_CNTL
blackout = RREG32(R700_MC_CITF_CNTL);
WREG32(R700_MC_CITF_CNTL, blackout);
tmp = RREG32(R700_MC_CITF_CNTL);
WREG32(R700_MC_CITF_CNTL, tmp);