drm/amdgpu: Make amdgpu_fence_emit() non-failing v2

dma_fence_wait(old, false) is not interruptible and cannot return an
error. Drop the unreachable error handling in amdgpu_fence_emit().

Since the function can no longer fail, convert amdgpu_fence_emit() to
return void and remove return value handling from all callers.

v2:
- Add comment explaining why dma_fence_wait(..., false)
  return value is ignored (Alex)

Suggested-by: Christian König <christian.koenig@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

4 files changed, 13 insertions, 24 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
index 1054d66c54fa..07568516c506 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
@@ -107,16 +107,14 @@ static void amdgpu_fence_save_fence_wptr_end(struct amdgpu_fence *af)
  * @flags: flags to pass into the subordinate .emit_fence() call
  *
  * Emits a fence command on the requested ring (all asics).
- * Returns 0 on success, -ENOMEM on failure.
  */
-int amdgpu_fence_emit(struct amdgpu_ring *ring, struct amdgpu_fence *af,
-		      unsigned int flags)
+void amdgpu_fence_emit(struct amdgpu_ring *ring, struct amdgpu_fence *af,
+		       unsigned int flags)
 {
 	struct amdgpu_device *adev = ring->adev;
 	struct dma_fence *fence;
 	struct dma_fence __rcu **ptr;
 	uint32_t seq;
-	int r;
 
 	fence = &af->base;
 	af->ring = ring;
@@ -141,10 +139,13 @@ int amdgpu_fence_emit(struct amdgpu_ring *ring, struct amdgpu_fence *af,
 		rcu_read_unlock();
 
 		if (old) {
-			r = dma_fence_wait(old, false);
+			/*
+			 * dma_fence_wait(old, false) is not interruptible.
+			 * It will not return an error in this case.
+			 * So we can safely ignore the return value.
+			 */
+			dma_fence_wait(old, false);
 			dma_fence_put(old);
-			if (r)
-				return r;
 		}
 	}
 
@@ -154,8 +155,6 @@ int amdgpu_fence_emit(struct amdgpu_ring *ring, struct amdgpu_fence *af,
 	 * emitting the fence would mess up the hardware ring buffer.
 	 */
 	rcu_assign_pointer(*ptr, dma_fence_get(fence));
-
-	return 0;
 }
 
 /**
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c
index bfccb03193d3..647b752ed2b5 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c
@@ -297,14 +297,7 @@ int amdgpu_ib_schedule(struct amdgpu_ring *ring, unsigned int num_ibs,
 		amdgpu_ring_init_cond_exec(ring, ring->cond_exe_gpu_addr);
 	}
 
-	r = amdgpu_fence_emit(ring, af, fence_flags);
-	if (r) {
-		dev_err(adev->dev, "failed to emit fence (%d)\n", r);
-		if (job && job->vmid)
-			amdgpu_vmid_reset(adev, ring->vm_hub, job->vmid);
-		amdgpu_ring_undo(ring);
-		goto free_fence;
-	}
+	amdgpu_fence_emit(ring, af, fence_flags);
 	*f = &af->base;
 	/* get a ref for the job */
 	if (job)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
index 1abd8fdb5cef..5a82db0888f0 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
@@ -172,8 +172,8 @@ void amdgpu_fence_driver_hw_init(struct amdgpu_device *adev);
 void amdgpu_fence_driver_hw_fini(struct amdgpu_device *adev);
 int amdgpu_fence_driver_sw_init(struct amdgpu_device *adev);
 void amdgpu_fence_driver_sw_fini(struct amdgpu_device *adev);
-int amdgpu_fence_emit(struct amdgpu_ring *ring, struct amdgpu_fence *af,
-		      unsigned int flags);
+void amdgpu_fence_emit(struct amdgpu_ring *ring, struct amdgpu_fence *af,
+		       unsigned int flags);
 int amdgpu_fence_emit_polling(struct amdgpu_ring *ring, uint32_t *s,
 			      uint32_t timeout);
 bool amdgpu_fence_process(struct amdgpu_ring *ring);
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index 83b8a41f559c..33efcb24090b 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -783,8 +783,7 @@ int amdgpu_vm_flush(struct amdgpu_ring *ring, struct amdgpu_job *job,
 	bool cleaner_shader_needed = false;
 	bool pasid_mapping_needed = false;
 	struct dma_fence *fence = NULL;
-	unsigned int patch;
-	int r;
+	unsigned int patch = 0;
 
 	if (amdgpu_vmid_had_gpu_reset(adev, id)) {
 		gds_switch_needed = true;
@@ -856,9 +855,7 @@ int amdgpu_vm_flush(struct amdgpu_ring *ring, struct amdgpu_job *job,
 	}
 
 	if (vm_flush_needed || pasid_mapping_needed || cleaner_shader_needed) {
-		r = amdgpu_fence_emit(ring, job->hw_vm_fence, 0);
-		if (r)
-			return r;
+		amdgpu_fence_emit(ring, job->hw_vm_fence, 0);
 		fence = &job->hw_vm_fence->base;
 		/* get a ref for the job */
 		dma_fence_get(fence);