[PATCH] drm/radeon: fix write back suspend regression with uvd

[j.glisse at gmail.com]

From: Jerome Glisse <jglisse at redhat.com>

UVD ring can't use scratch thus it does need writeback buffer to keep
a valid address or radeon_ring_backup will trigger a kernel fault.

It's ok to not unpin the write back buffer on suspend as it leave in
gtt and thus does not need eviction.

Reported and tracked by Wojtek <wojtask9 at wp.pl>

Signed-off-by: Jerome Glisse <jglisse at redhat.com>
---
 drivers/gpu/drm/radeon/radeon_device.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/radeon/radeon_device.c b/drivers/gpu/drm/radeon/radeon_device.c
index 1899738..eb8068a 100644
--- a/drivers/gpu/drm/radeon/radeon_device.c
+++ b/drivers/gpu/drm/radeon/radeon_device.c
@@ -244,16 +244,6 @@ void radeon_scratch_free(struct radeon_device *rdev, uint32_t reg)
  */
 void radeon_wb_disable(struct radeon_device *rdev)
 {
-	int r;
-
-	if (rdev->wb.wb_obj) {
-		r = radeon_bo_reserve(rdev->wb.wb_obj, false);
-		if (unlikely(r != 0))
-			return;
-		radeon_bo_kunmap(rdev->wb.wb_obj);
-		radeon_bo_unpin(rdev->wb.wb_obj);
-		radeon_bo_unreserve(rdev->wb.wb_obj);
-	}
 	rdev->wb.enabled = false;
 }
 
@@ -269,6 +259,11 @@ void radeon_wb_fini(struct radeon_device *rdev)
 {
 	radeon_wb_disable(rdev);
 	if (rdev->wb.wb_obj) {
+		if (!radeon_bo_reserve(rdev->wb.wb_obj, false)) {
+			radeon_bo_kunmap(rdev->wb.wb_obj);
+			radeon_bo_unpin(rdev->wb.wb_obj);
+			radeon_bo_unreserve(rdev->wb.wb_obj);
+		}
 		radeon_bo_unref(&rdev->wb.wb_obj);
 		rdev->wb.wb = NULL;
 		rdev->wb.wb_obj = NULL;
-- 
1.7.11.7