[PATCH] drm/radeon: stop poisoning the GART TLB v2

[Christian König]

From: Christian König <christian.koenig at amd.com>

When we set the valid bit on invalid GART entries they are
loaded into the TLB when an adjacent entry is loaded. This
poisons the TLB with invalid entries which are sometimes
not correctly removed on TLB flush.

v2: rebased on 3.15 for stable inclusion

Signed-off-by: Christian König <christian.koenig at amd.com>
Cc: stable at vger.kernel.org
Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
---
 drivers/gpu/drm/radeon/rs600.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/radeon/rs600.c b/drivers/gpu/drm/radeon/rs600.c
index 72d3616..95b693c 100644
--- a/drivers/gpu/drm/radeon/rs600.c
+++ b/drivers/gpu/drm/radeon/rs600.c
@@ -646,8 +646,10 @@ int rs600_gart_set_page(struct radeon_device *rdev, int i, uint64_t addr)
 		return -EINVAL;
 	}
 	addr = addr & 0xFFFFFFFFFFFFF000ULL;
-	addr |= R600_PTE_VALID | R600_PTE_SYSTEM | R600_PTE_SNOOPED;
-	addr |= R600_PTE_READABLE | R600_PTE_WRITEABLE;
+	if (addr != rdev->dummy_page.addr)
+		addr |= R600_PTE_VALID | R600_PTE_READABLE |
+			R600_PTE_WRITEABLE;
+	addr |= R600_PTE_SYSTEM | R600_PTE_SNOOPED;
 	writeq(addr, ptr + (i * 8));
 	return 0;
 }
-- 
1.9.1