EVERGREEN_CRTC_DISP_READ_REQUEST_DISABLE
tmp |= EVERGREEN_CRTC_DISP_READ_REQUEST_DISABLE;
tmp &= ~EVERGREEN_CRTC_DISP_READ_REQUEST_DISABLE;
if (!(tmp & EVERGREEN_CRTC_DISP_READ_REQUEST_DISABLE)) {
tmp |= EVERGREEN_CRTC_DISP_READ_REQUEST_DISABLE;
tmp &= ~EVERGREEN_CRTC_DISP_READ_REQUEST_DISABLE;