if (!(tmp & EVERGREEN_CRTC_BLANK_DATA_EN)) {
                                        radeon_wait_for_vblank(rdev, i);
                                        tmp |= EVERGREEN_CRTC_BLANK_DATA_EN;
+                                       WREG32(EVERGREEN_CRTC_UPDATE_LOCK + crtc_offsets[i], 1);
                                        WREG32(EVERGREEN_CRTC_BLANK_CONTROL + crtc_offsets[i], tmp);
+                                       WREG32(EVERGREEN_CRTC_UPDATE_LOCK + crtc_offsets[i], 0);
                                }
                        } else {
                                tmp = RREG32(EVERGREEN_CRTC_CONTROL + crtc_offsets[i]);
                                if (!(tmp & EVERGREEN_CRTC_DISP_READ_REQUEST_DISABLE)) {
                                        radeon_wait_for_vblank(rdev, i);
                                        tmp |= EVERGREEN_CRTC_DISP_READ_REQUEST_DISABLE;
+                                       WREG32(EVERGREEN_CRTC_UPDATE_LOCK + crtc_offsets[i], 1);
                                        WREG32(EVERGREEN_CRTC_CONTROL + crtc_offsets[i], tmp);
+                                       WREG32(EVERGREEN_CRTC_UPDATE_LOCK + crtc_offsets[i], 0);
                                }
                        }
                        /* wait for the next frame */
                        if (ASIC_IS_DCE6(rdev)) {
                                tmp = RREG32(EVERGREEN_CRTC_BLANK_CONTROL + crtc_offsets[i]);
                                tmp |= EVERGREEN_CRTC_BLANK_DATA_EN;
+                               WREG32(EVERGREEN_CRTC_UPDATE_LOCK + crtc_offsets[i], 1);
                                WREG32(EVERGREEN_CRTC_BLANK_CONTROL + crtc_offsets[i], tmp);
+                               WREG32(EVERGREEN_CRTC_UPDATE_LOCK + crtc_offsets[i], 0);
                        } else {
                                tmp = RREG32(EVERGREEN_CRTC_CONTROL + crtc_offsets[i]);
                                tmp &= ~EVERGREEN_CRTC_DISP_READ_REQUEST_DISABLE;
+                               WREG32(EVERGREEN_CRTC_UPDATE_LOCK + crtc_offsets[i], 1);
                                WREG32(EVERGREEN_CRTC_CONTROL + crtc_offsets[i], tmp);
+                               WREG32(EVERGREEN_CRTC_UPDATE_LOCK + crtc_offsets[i], 0);
                        }
                        /* wait for the next frame */
                        frame_count = radeon_get_vblank_counter(rdev, i);