drm/amd: add parent for sched fence

Parent of sched fence is hw fence which is to signal sched fence.
Signed-off-by: Chunming Zhou <David1.Zhou@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/scheduler/gpu_scheduler.c

@@ -516,6 +516,7 @@ static int amd_sched_main(void *param)
 		fence = sched->ops->run_job(sched_job);
 		amd_sched_fence_scheduled(s_fence);
 		if (fence) {
+			s_fence->parent = fence_get(fence);
 			r = fence_add_callback(fence, &s_fence->cb,
 					       amd_sched_process_job);
 			if (r == -ENOENT)

drivers/gpu/drm/amd/scheduler/gpu_scheduler.h

@@ -69,6 +69,7 @@ struct amd_sched_fence {
 	struct fence                    scheduled;
 	struct fence                    finished;
 	struct fence_cb                 cb;
+	struct fence                    *parent;
 	struct amd_gpu_scheduler	*sched;
 	spinlock_t			lock;
 	void                            *owner;

drivers/gpu/drm/amd/scheduler/sched_fence.c

@@ -98,6 +98,7 @@ static void amd_sched_fence_free(struct rcu_head *rcu)
 	struct fence *f = container_of(rcu, struct fence, rcu);
 	struct amd_sched_fence *fence = to_amd_sched_fence(f);
 
+	fence_put(fence->parent);
 	kmem_cache_free(sched_fence_slab, fence);
 }