[PATCH 3.14 19/98] drm/radeon: work around a hw bug in MGCG on CIK

[Greg Kroah-Hartman]

3.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Alex Deucher <alexander.deucher@xxxxxxx>

commit 4bb62c95a7e781a238b2ab374f34b1bf91e01ddc upstream.

Always need to set bit 0 of RLC_CGTT_MGCG_OVERRIDE
to avoid unreliable doorbell updates in some cases.

Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/gpu/drm/radeon/cik.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/gpu/drm/radeon/cik.c
+++ b/drivers/gpu/drm/radeon/cik.c
@@ -5879,6 +5879,7 @@ static void cik_enable_mgcg(struct radeo
 		}
 
 		orig = data = RREG32(RLC_CGTT_MGCG_OVERRIDE);
+		data |= 0x00000001;
 		data &= 0xfffffffd;
 		if (orig != data)
 			WREG32(RLC_CGTT_MGCG_OVERRIDE, data);
@@ -5910,7 +5911,7 @@ static void cik_enable_mgcg(struct radeo
 		}
 	} else {
 		orig = data = RREG32(RLC_CGTT_MGCG_OVERRIDE);
-		data |= 0x00000002;
+		data |= 0x00000003;
 		if (orig != data)
 			WREG32(RLC_CGTT_MGCG_OVERRIDE, data);
 


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