[PATCH v3 3/8] amdgpu: use trace_dma_fence_sync_to in amdgpu_fence_sync

[Pierre-Eric Pelloux-Prayer]

This makes it possible to understand the dependencies between jobs.
Possible usage of this trace:
* stuttering issues like Mesa !9189
* incorrect synchronization: I don't have a link for this one, but having
  these events was very useful to debug a virtio-gpu / native-context /
  radeonsi sync issue

I have prototype code using this in UMR, as can be see here:
   https://gitlab.freedesktop.org/tomstdenis/umr/-/merge_requests/37

v2: add a macro since every caller passes __func__ as the reason parameter

Signed-off-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c | 9 +++++++--
 drivers/gpu/drm/amd/amdgpu/amdgpu_sync.h | 4 +++-
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c
index 1b013a44ca99..9a3fdc4be51e 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c
@@ -30,6 +30,7 @@
  */
 
 #include <linux/dma-fence-chain.h>
+#include <trace/events/dma_fence.h>
 
 #include "amdgpu.h"
 #include "amdgpu_trace.h"
@@ -145,14 +146,16 @@ static bool amdgpu_sync_add_later(struct amdgpu_sync *sync, struct dma_fence *f)
 }
 
 /**
- * amdgpu_sync_fence - remember to sync to this fence
+ * amdgpu_sync_fence_with_reason - remember to sync to this fence
  *
  * @sync: sync object to add fence to
  * @f: fence to sync to
+ * @reason: why do we sync to this fence
  *
  * Add the fence to the sync object.
  */
-int amdgpu_sync_fence(struct amdgpu_sync *sync, struct dma_fence *f)
+int amdgpu_sync_fence_with_reason(struct amdgpu_sync *sync, struct dma_fence *f,
+				  const char *reason)
 {
 	struct amdgpu_sync_entry *e;
 
@@ -166,6 +169,8 @@ int amdgpu_sync_fence(struct amdgpu_sync *sync, struct dma_fence *f)
 	if (!e)
 		return -ENOMEM;
 
+	trace_dma_fence_used_as_dependency(f, reason);
+
 	hash_add(sync->fences, &e->node, f->context);
 	e->fence = dma_fence_get(f);
 	return 0;
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.h
index cf1e9e858efd..52e7306801de 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.h
@@ -47,7 +47,9 @@ struct amdgpu_sync {
 };
 
 void amdgpu_sync_create(struct amdgpu_sync *sync);
-int amdgpu_sync_fence(struct amdgpu_sync *sync, struct dma_fence *f);
+int amdgpu_sync_fence_with_reason(struct amdgpu_sync *sync, struct dma_fence *f,
+				  const char *reason);
+#define amdgpu_sync_fence(s, f) amdgpu_sync_fence_with_reason(s, f, __func__)
 int amdgpu_sync_resv(struct amdgpu_device *adev, struct amdgpu_sync *sync,
 		     struct dma_resv *resv, enum amdgpu_sync_mode mode,
 		     void *owner);
-- 
2.40.1