drm/radeon: fix write back suspend regression with uvd v2

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.

v2: Fix the uvd case.

Reported and tracked by Wojtek <wojtask9@wp.pl>
Signed-off-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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;
@@ -295,7 +290,6 @@ int radeon_wb_init(struct radeon_device *rdev)
 			dev_warn(rdev->dev, "(%d) create WB bo failed\n", r);
 			return r;
 		}
-	}
 		r = radeon_bo_reserve(rdev->wb.wb_obj, false);
 		if (unlikely(r != 0)) {
 			radeon_wb_fini(rdev);
@@ -316,6 +310,7 @@ int radeon_wb_init(struct radeon_device *rdev)
 			radeon_wb_fini(rdev);
 			return r;
 		}
+	}
 
 	/* clear wb memory */
 	memset((char *)rdev->wb.wb, 0, RADEON_GPU_PAGE_SIZE);

drivers/gpu/drm/radeon/radeon_fence.c

@@ -63,7 +63,9 @@ static void radeon_fence_write(struct radeon_device *rdev, u32 seq, int ring)
 {
 	struct radeon_fence_driver *drv = &rdev->fence_drv[ring];
 	if (likely(rdev->wb.enabled || !drv->scratch_reg)) {
+		if (drv->cpu_addr) {
 			*drv->cpu_addr = cpu_to_le32(seq);
+		}
 	} else {
 		WREG32(drv->scratch_reg, seq);
 	}
@@ -84,7 +86,11 @@ static u32 radeon_fence_read(struct radeon_device *rdev, int ring)
 	u32 seq = 0;
 
 	if (likely(rdev->wb.enabled || !drv->scratch_reg)) {
+		if (drv->cpu_addr) {
 			seq = le32_to_cpu(*drv->cpu_addr);
+		} else {
+			seq = lower_32_bits(atomic64_read(&drv->last_seq));
+		}
 	} else {
 		seq = RREG32(drv->scratch_reg);
 	}

drivers/gpu/drm/radeon/radeon_uvd.c

@@ -159,7 +159,17 @@ int radeon_uvd_suspend(struct radeon_device *rdev)
 	if (!r) {
 		radeon_bo_kunmap(rdev->uvd.vcpu_bo);
 		radeon_bo_unpin(rdev->uvd.vcpu_bo);
+		rdev->uvd.cpu_addr = NULL;
+		if (!radeon_bo_pin(rdev->uvd.vcpu_bo, RADEON_GEM_DOMAIN_CPU, NULL)) {
+			radeon_bo_kmap(rdev->uvd.vcpu_bo, &rdev->uvd.cpu_addr);
+		}
 		radeon_bo_unreserve(rdev->uvd.vcpu_bo);
+
+		if (rdev->uvd.cpu_addr) {
+			radeon_fence_driver_start_ring(rdev, R600_RING_TYPE_UVD_INDEX);
+		} else {
+			rdev->fence_drv[R600_RING_TYPE_UVD_INDEX].cpu_addr = NULL;
+		}
 	}
 	return r;
 }
@@ -178,6 +188,10 @@ int radeon_uvd_resume(struct radeon_device *rdev)
 		return r;
 	}
 
+	/* Have been pin in cpu unmap unpin */
+	radeon_bo_kunmap(rdev->uvd.vcpu_bo);
+	radeon_bo_unpin(rdev->uvd.vcpu_bo);
+
 	r = radeon_bo_pin(rdev->uvd.vcpu_bo, RADEON_GEM_DOMAIN_VRAM,
 			  &rdev->uvd.gpu_addr);
 	if (r) {