drm/radeon: disable the crtcs in mc_stop (evergreen+) (v2)

Just disabling the mem requests should be enough, but
that doesn't seem to work correctly on efi systems.

May fix:
https://bugs.freedesktop.org/show_bug.cgi?id=57567
https://bugs.freedesktop.org/show_bug.cgi?id=43655
https://bugzilla.kernel.org/show_bug.cgi?id=56441

v2: blank displays first, then disable.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

drivers/gpu/drm/radeon/evergreen.c

@@ -1574,15 +1574,18 @@ void evergreen_mc_stop(struct radeon_device *rdev, struct evergreen_mc_save *sav
 				tmp = RREG32(EVERGREEN_CRTC_BLANK_CONTROL + crtc_offsets[i]);
 				if (!(tmp & EVERGREEN_CRTC_BLANK_DATA_EN)) {
 					radeon_wait_for_vblank(rdev, i);
+					WREG32(EVERGREEN_CRTC_UPDATE_LOCK + crtc_offsets[i], 1);
 					tmp |= EVERGREEN_CRTC_BLANK_DATA_EN;
 					WREG32(EVERGREEN_CRTC_BLANK_CONTROL + crtc_offsets[i], tmp);
 				}
 			} else {
 				tmp = RREG32(EVERGREEN_CRTC_CONTROL + crtc_offsets[i]);
 				if (!(tmp & EVERGREEN_CRTC_DISP_READ_REQUEST_DISABLE)) {
 					radeon_wait_for_vblank(rdev, i);
+					WREG32(EVERGREEN_CRTC_UPDATE_LOCK + crtc_offsets[i], 1);
 					tmp |= EVERGREEN_CRTC_DISP_READ_REQUEST_DISABLE;
 					WREG32(EVERGREEN_CRTC_CONTROL + crtc_offsets[i], tmp);
+					WREG32(EVERGREEN_CRTC_UPDATE_LOCK + crtc_offsets[i], 0);
 				}
 			}
 			/* wait for the next frame */
@@ -1592,6 +1595,15 @@ void evergreen_mc_stop(struct radeon_device *rdev, struct evergreen_mc_save *sav
 					break;
 				udelay(1);
 			}
+
+			/* XXX this is a hack to avoid strange behavior with EFI on certain systems */
+			WREG32(EVERGREEN_CRTC_UPDATE_LOCK + crtc_offsets[i], 1);
+			tmp = RREG32(EVERGREEN_CRTC_CONTROL + crtc_offsets[i]);
+			tmp &= ~EVERGREEN_CRTC_MASTER_EN;
+			WREG32(EVERGREEN_CRTC_CONTROL + crtc_offsets[i], tmp);
+			WREG32(EVERGREEN_CRTC_UPDATE_LOCK + crtc_offsets[i], 0);
+			save->crtc_enabled[i] = false;
+			/* ***** */
 		} else {
 			save->crtc_enabled[i] = false;
 		}