drm/radeon: Don't flush the GART TLB if rdev->gart.ptr == NULL

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@amd.com>
Signed-off-by: Michel Dänzer <michel.daenzer@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

1 files changed, 8 insertions, 4 deletions

diff --git a/drivers/gpu/drm/radeon/radeon_gart.c b/drivers/gpu/drm/radeon/radeon_gart.c
index 5450fa95a47e..c4777c8d0312 100644
--- a/drivers/gpu/drm/radeon/radeon_gart.c
+++ b/drivers/gpu/drm/radeon/radeon_gart.c
@@ -260,8 +260,10 @@ void radeon_gart_unbind(struct radeon_device *rdev, unsigned offset,
                         }
                 }
         }
-        mb();
-        radeon_gart_tlb_flush(rdev);
+        if (rdev->gart.ptr) {
+                mb();
+                radeon_gart_tlb_flush(rdev);
+        }
 }
 
 /**
@@ -306,8 +308,10 @@ int radeon_gart_bind(struct radeon_device *rdev, unsigned offset,
                         page_base += RADEON_GPU_PAGE_SIZE;
                 }
         }
-        mb();
-        radeon_gart_tlb_flush(rdev);
+        if (rdev->gart.ptr) {
+                mb();
+                radeon_gart_tlb_flush(rdev);
+        }
         return 0;
 }