drm/amdgpu: amdgpu_device_recover_vram always failed if only one node in shadow_list

amdgpu_bo_restore_shadow would assign zero to r if succeeded.
r would remain zero if there is only one node in shadow_list.
current code would always return failure when r <= 0.
restart the timeout for each wait was a rather problematic bug as well.
The value of tmo SHOULD be changed, otherwise we wait tmo jiffies on each loop.
Signed-off-by: Wentao Lou <Wentao.Lou@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_device.c

@@ -3173,11 +3173,16 @@ static int amdgpu_device_recover_vram(struct amdgpu_device *adev)
 			break;
 
 		if (fence) {
-			r = dma_fence_wait_timeout(fence, false, tmo);
+			tmo = dma_fence_wait_timeout(fence, false, tmo);
 			dma_fence_put(fence);
 			fence = next;
-			if (r <= 0)
+			if (tmo == 0) {
+				r = -ETIMEDOUT;
 				break;
+			} else if (tmo < 0) {
+				r = tmo;
+				break;
+			}
 		} else {
 			fence = next;
 		}
@@ -3188,8 +3193,8 @@ static int amdgpu_device_recover_vram(struct amdgpu_device *adev)
 		tmo = dma_fence_wait_timeout(fence, false, tmo);
 	dma_fence_put(fence);
 
-	if (r <= 0 || tmo <= 0) {
-		DRM_ERROR("recover vram bo from shadow failed\n");
+	if (r < 0 || tmo <= 0) {
+		DRM_ERROR("recover vram bo from shadow failed, r is %ld, tmo is %ld\n", r, tmo);
 		return -EIO;
 	}