mmHDMI_GC
WREG32(mmHDMI_GC + dig->afmt->offset, 0); /* unset HDMI_GC_AVMUTE */
tmp = RREG32(mmHDMI_GC + dig->afmt->offset);
WREG32(mmHDMI_GC + dig->afmt->offset, tmp);
WREG32(mmHDMI_GC + offset, 0); /* unset HDMI_GC_AVMUTE */