[PATCH 2/3] drm/amdgpu: drop the sched_sync

[Monk Liu]

Reasons to drop it:

1) simplify the code: just introduce field member "need_pipe_sync"
for job is good enough to tell if the explicit dependency fence
need followed by a pipeline sync.

2) after GPU_recover the explicit fence from sched_syn will not
come back so the required pipeline_sync following it is missed,
consider scenario below:
>now on ring buffer:
Job-A -> pipe_sync -> Job-B
>TDR occured on Job-A, and after GPU recover:
>now on ring buffer:
Job-A -> Job-B

because the fence from sched_sync is used and freed after ib_schedule
in first time, it will never come back, with this patch this issue
could be avoided.

Signed-off-by: Monk Liu <Monk.Liu at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c  | 16 ++++++----------
 drivers/gpu/drm/amd/amdgpu/amdgpu_job.c | 14 +++-----------
 drivers/gpu/drm/amd/amdgpu/amdgpu_job.h |  3 +--
 3 files changed, 10 insertions(+), 23 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c
index c48207b3..ac7d2da 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c
@@ -122,7 +122,6 @@ int amdgpu_ib_schedule(struct amdgpu_ring *ring, unsigned num_ibs,
 {
 	struct amdgpu_device *adev = ring->adev;
 	struct amdgpu_ib *ib = &ibs[0];
-	struct dma_fence *tmp = NULL;
 	bool skip_preamble, need_ctx_switch;
 	unsigned patch_offset = ~0;
 	struct amdgpu_vm *vm;
@@ -166,16 +165,13 @@ int amdgpu_ib_schedule(struct amdgpu_ring *ring, unsigned num_ibs,
 	}
 
 	need_ctx_switch = ring->current_ctx != fence_ctx;
-	if (ring->funcs->emit_pipeline_sync && job &&
-	    ((tmp = amdgpu_sync_get_fence(&job->sched_sync, NULL)) ||
-	     (amdgpu_sriov_vf(adev) && need_ctx_switch) ||
-	     amdgpu_vm_need_pipeline_sync(ring, job))) {
-		need_pipe_sync = true;
 
-		if (tmp)
-			trace_amdgpu_ib_pipe_sync(job, tmp);
-
-		dma_fence_put(tmp);
+	if (ring->funcs->emit_pipeline_sync && job) {
+		if ((need_ctx_switch && amdgpu_sriov_vf(adev)) ||
+			amdgpu_vm_need_pipeline_sync(ring, job))
+			need_pipe_sync = true;
+		else if (job->need_pipe_sync)
+			need_pipe_sync = true;
 	}
 
 	if (ring->funcs->insert_start)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
index 1d71f8c..dae997d 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
@@ -71,7 +71,6 @@ int amdgpu_job_alloc(struct amdgpu_device *adev, unsigned num_ibs,
 	(*job)->num_ibs = num_ibs;
 
 	amdgpu_sync_create(&(*job)->sync);
-	amdgpu_sync_create(&(*job)->sched_sync);
 	(*job)->vram_lost_counter = atomic_read(&adev->vram_lost_counter);
 	(*job)->vm_pd_addr = AMDGPU_BO_INVALID_OFFSET;
 
@@ -117,7 +116,6 @@ static void amdgpu_job_free_cb(struct drm_sched_job *s_job)
 	amdgpu_ring_priority_put(ring, s_job->s_priority);
 	dma_fence_put(job->fence);
 	amdgpu_sync_free(&job->sync);
-	amdgpu_sync_free(&job->sched_sync);
 	kfree(job);
 }
 
@@ -127,7 +125,6 @@ void amdgpu_job_free(struct amdgpu_job *job)
 
 	dma_fence_put(job->fence);
 	amdgpu_sync_free(&job->sync);
-	amdgpu_sync_free(&job->sched_sync);
 	kfree(job);
 }
 
@@ -182,14 +179,9 @@ static struct dma_fence *amdgpu_job_dependency(struct drm_sched_job *sched_job,
 	bool need_pipe_sync = false;
 	int r;
 
-	fence = amdgpu_sync_get_fence(&job->sync, &need_pipe_sync);
-	if (fence && need_pipe_sync) {
-		if (drm_sched_dependency_optimized(fence, s_entity)) {
-			r = amdgpu_sync_fence(ring->adev, &job->sched_sync,
-					      fence, false);
-			if (r)
-				DRM_ERROR("Error adding fence (%d)\n", r);
-		}
+	if (fence && need_pipe_sync && drm_sched_dependency_optimized(fence, s_entity)) {
+		trace_amdgpu_ib_pipe_sync(job, fence);
+		job->need_pipe_sync = true;
 	}
 
 	while (fence == NULL && vm && !job->vmid) {
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.h
index e1b46a6..c1d00f0 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.h
@@ -41,7 +41,6 @@ struct amdgpu_job {
 	struct drm_sched_job    base;
 	struct amdgpu_vm	*vm;
 	struct amdgpu_sync	sync;
-	struct amdgpu_sync	sched_sync;
 	struct amdgpu_ib	*ibs;
 	struct dma_fence	*fence; /* the hw fence */
 	uint32_t		preamble_status;
@@ -59,7 +58,7 @@ struct amdgpu_job {
 	/* user fence handling */
 	uint64_t		uf_addr;
 	uint64_t		uf_sequence;
-
+	bool            need_pipe_sync; /* require a pipeline sync for this job */
 };
 
 int amdgpu_job_alloc(struct amdgpu_device *adev, unsigned num_ibs,
-- 
2.7.4