[PATCH] drm: fix to radeon driver for HD 6450

[Chris Staite]

From: Christopher Staite <chris@xxxxxxxxxxxxxxxxxx>

Fix commit 62444b7462a2b98bc78d68736c03a7c4e66ba7e2 for HD 6450.  The stop and resume causes the screen to glitch and the X server to reboot constantly.  Re-instating the UPDATE_LOCK fixes the issue in tests on the v3.6.11 stable, and the code has not been altered to fix this since.

Signed-off-by: Christopher Staite <chris@xxxxxxxxxxxxxxxxxx>



--- drivers/gpu/drm/radeon/evergreen.c.org	2013-01-25 17:45:06.000000000 +0000
+++ drivers/gpu/drm/radeon/evergreen.c	2013-01-25 17:48:14.000000000 +0000
@@ -1320,7 +1320,9 @@ void evergreen_mc_stop(struct radeon_dev
 				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 */
@@ -1382,7 +1384,9 @@ void evergreen_mc_resume(struct radeon_d
 			} 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);--
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