[PATCH] dma-buf: keep the signaling time of merged fences

[Jessie Hao]

Hi Christian,
After applying the patch, the below android CTS cases can pass:
CtsDeqpTestCases dEQP-EGL.functional.get_frame_timestamps*
Thanks for taking care of this.

Tested-by: Jessie Hao <juan.hao at nxp.com>

-----Original Message-----
From: Christian König <ckoenig.leichtzumerken at gmail.com> 
Sent: Wednesday, June 21, 2023 3:32 PM
To: Jessie Hao <juan.hao at nxp.com>; dri-devel at lists.freedesktop.org
Cc: Christian König <christian.koenig at amd.com>; stable at vger.kernel.org
Subject: [PATCH] dma-buf: keep the signaling time of merged fences


Some Android CTS is testing for that.

Signed-off-by: Christian König <christian.koenig at amd.com>
CC: stable at vger.kernel.org
---
 drivers/dma-buf/dma-fence-unwrap.c | 11 +++++++++--
 drivers/dma-buf/dma-fence.c        |  5 +++--
 drivers/gpu/drm/drm_syncobj.c      |  2 +-
 include/linux/dma-fence.h          |  2 +-
 4 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/drivers/dma-buf/dma-fence-unwrap.c b/drivers/dma-buf/dma-fence-unwrap.c
index 7002bca792ff..06eb91306c01 100644
--- a/drivers/dma-buf/dma-fence-unwrap.c
+++ b/drivers/dma-buf/dma-fence-unwrap.c
@@ -66,18 +66,25 @@ struct dma_fence *__dma_fence_unwrap_merge(unsigned int num_fences,  {
        struct dma_fence_array *result;
        struct dma_fence *tmp, **array;
+       ktime_t timestamp;
        unsigned int i;
        size_t count;

        count = 0;
+       timestamp = ns_to_ktime(0);
        for (i = 0; i < num_fences; ++i) {
-               dma_fence_unwrap_for_each(tmp, &iter[i], fences[i])
+               dma_fence_unwrap_for_each(tmp, &iter[i], fences[i]) {
                        if (!dma_fence_is_signaled(tmp))
                                ++count;
+                       else if (test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT,
+                                         &tmp->flags) &&
+                                ktime_after(tmp->timestamp, timestamp))
+                               timestamp = tmp->timestamp;
+               }
        }

        if (count == 0)
-               return dma_fence_get_stub();
+               return dma_fence_allocate_private_stub(timestamp);

        array = kmalloc_array(count, sizeof(*array), GFP_KERNEL);
        if (!array)
diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c index f177c56269bb..ad076f208760 100644
--- a/drivers/dma-buf/dma-fence.c
+++ b/drivers/dma-buf/dma-fence.c
@@ -150,10 +150,11 @@ EXPORT_SYMBOL(dma_fence_get_stub);

 /**
  * dma_fence_allocate_private_stub - return a private, signaled fence
+ * @timestamp: timestamp when the fence was signaled
  *
  * Return a newly allocated and signaled stub fence.
  */
-struct dma_fence *dma_fence_allocate_private_stub(void)
+struct dma_fence *dma_fence_allocate_private_stub(ktime_t timestamp)
 {
        struct dma_fence *fence;

@@ -169,7 +170,7 @@ struct dma_fence *dma_fence_allocate_private_stub(void)
        set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
                &fence->flags);

-       dma_fence_signal(fence);
+       dma_fence_signal_timestamp(fence, timestamp);

        return fence;
 }
diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c index 0c2be8360525..04589a35eb09 100644
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -353,7 +353,7 @@ EXPORT_SYMBOL(drm_syncobj_replace_fence);
  */
 static int drm_syncobj_assign_null_handle(struct drm_syncobj *syncobj)  {
-       struct dma_fence *fence = dma_fence_allocate_private_stub();
+       struct dma_fence *fence = 
+ dma_fence_allocate_private_stub(ktime_get());

        if (IS_ERR(fence))
                return PTR_ERR(fence);
diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h index d54b595a0fe0..0d678e9a7b24 100644
--- a/include/linux/dma-fence.h
+++ b/include/linux/dma-fence.h
@@ -606,7 +606,7 @@ static inline signed long dma_fence_wait(struct dma_fence *fence, bool intr)  void dma_fence_set_deadline(struct dma_fence *fence, ktime_t deadline);

 struct dma_fence *dma_fence_get_stub(void); -struct dma_fence *dma_fence_allocate_private_stub(void);
+struct dma_fence *dma_fence_allocate_private_stub(ktime_t timestamp);
 u64 dma_fence_context_alloc(unsigned num);

 extern const struct dma_fence_ops dma_fence_array_ops;
--
2.34.1