linux-kernel - [PATCH 3.2 091/110] drm/radeon: Don't flush the GART TLB if rdev->gart.ptr == NULL

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Message-ID: <lsq.1439201551.358305638@decadent.org.uk>
Date:	Mon, 10 Aug 2015 12:12:31 +0200
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org,
	"Alex Deucher" <alexander.deucher@....com>,
	"Christian König" <christian.koenig@....com>,
	"Michel Dänzer" <michel.daenzer@....com>
Subject: [PATCH 3.2 091/110] drm/radeon: Don't flush the GART TLB if
 rdev->gart.ptr == NULL

3.2.71-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Michel Dänzer <michel.daenzer@....com>

commit 233709d2cd6bbaaeda0aeb8d11f6ca7f98563b39 upstream.

This can be the case when the GPU is powered off, e.g. via vgaswitcheroo
or runpm. When the GPU is powered up again, radeon_gart_table_vram_pin
flushes the TLB after setting rdev->gart.ptr to non-NULL.

Fixes panic on powering off R7xx GPUs.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=61529
Reviewed-by: Christian König <christian.koenig@....com>
Signed-off-by: Michel Dänzer <michel.daenzer@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/gpu/drm/radeon/radeon_gart.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

--- a/drivers/gpu/drm/radeon/radeon_gart.c
+++ b/drivers/gpu/drm/radeon/radeon_gart.c
@@ -171,8 +171,10 @@ void radeon_gart_unbind(struct radeon_de
 			}
 		}
 	}
-	mb();
-	radeon_gart_tlb_flush(rdev);
+	if (rdev->gart.ptr) {
+		mb();
+		radeon_gart_tlb_flush(rdev);
+	}
 }
 
 int radeon_gart_bind(struct radeon_device *rdev, unsigned offset,
@@ -217,8 +219,10 @@ int radeon_gart_bind(struct radeon_devic
 			}
 		}
 	}
-	mb();
-	radeon_gart_tlb_flush(rdev);
+	if (rdev->gart.ptr) {
+		mb();
+		radeon_gart_tlb_flush(rdev);
+	}
 	return 0;
 }
 

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