drm/radeon: disable the crtcs in mc_stop (r5xx-r7xx) (v2)

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

v2: blank displays first, then disable.
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

drivers/gpu/drm/radeon/r500_reg.h

@@ -360,6 +360,7 @@
 
 #define AVIVO_D1MODE_MASTER_UPDATE_LOCK                         0x60e0
 #define AVIVO_D1MODE_MASTER_UPDATE_MODE                         0x60e4
+#define AVIVO_D1CRTC_UPDATE_LOCK                                0x60e8
 
 /* master controls */
 #define AVIVO_DC_CRTC_MASTER_EN                                 0x60f8

drivers/gpu/drm/radeon/rv515.c

@@ -303,8 +303,10 @@ void rv515_mc_stop(struct radeon_device *rdev, struct rv515_mc_save *save)
 			tmp = RREG32(AVIVO_D1CRTC_CONTROL + crtc_offsets[i]);
 			if (!(tmp & AVIVO_CRTC_DISP_READ_REQUEST_DISABLE)) {
 				radeon_wait_for_vblank(rdev, i);
+				WREG32(AVIVO_D1CRTC_UPDATE_LOCK + crtc_offsets[i], 1);
 				tmp |= AVIVO_CRTC_DISP_READ_REQUEST_DISABLE;
 				WREG32(AVIVO_D1CRTC_CONTROL + crtc_offsets[i], tmp);
+				WREG32(AVIVO_D1CRTC_UPDATE_LOCK + crtc_offsets[i], 0);
 			}
 			/* wait for the next frame */
 			frame_count = radeon_get_vblank_counter(rdev, i);
@@ -313,6 +315,15 @@ void rv515_mc_stop(struct radeon_device *rdev, struct rv515_mc_save *save)
 					break;
 				udelay(1);
 			}
+
+			/* XXX this is a hack to avoid strange behavior with EFI on certain systems */
+			WREG32(AVIVO_D1CRTC_UPDATE_LOCK + crtc_offsets[i], 1);
+			tmp = RREG32(AVIVO_D1CRTC_CONTROL + crtc_offsets[i]);
+			tmp &= ~AVIVO_CRTC_EN;
+			WREG32(AVIVO_D1CRTC_CONTROL + crtc_offsets[i], tmp);
+			WREG32(AVIVO_D1CRTC_UPDATE_LOCK + crtc_offsets[i], 0);
+			save->crtc_enabled[i] = false;
+			/* ***** */
 		} else {
 			save->crtc_enabled[i] = false;
 		}