Re: [PATCH v2 1/4] drm/sched: Enable signaling for finished fence

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 




On 2022-09-07 02:37, Christian König wrote:
Am 06.09.22 um 21:55 schrieb Andrey Grodzovsky:

On 2022-09-06 02:34, Christian König wrote:
Am 05.09.22 um 18:34 schrieb Arvind Yadav:
Here's enabling software signaling for finished fence.

Signed-off-by: Arvind Yadav <Arvind.Yadav@xxxxxxx>
---

Changes in v1 :
1- Addressing Christian's comment to remove CONFIG_DEBUG_FS check from
this patch.
2- The version of this patch is also changed and previously
it was [PATCH 2/4]

---
  drivers/gpu/drm/scheduler/sched_main.c | 2 ++
  1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
index e0ab14e0fb6b..fe72de0e2911 100644
--- a/drivers/gpu/drm/scheduler/sched_main.c
+++ b/drivers/gpu/drm/scheduler/sched_main.c
@@ -962,6 +962,8 @@ static int drm_sched_main(void *param)
              /* Drop for original kref_init of the fence */
              dma_fence_put(fence);
  + dma_fence_enable_sw_signaling(&s_fence->finished);

Ok, this makes it a lot clearer. Previously I though that we have some bug in dma_fence_add_callback().

This is essentially the wrong place to call this, the finished fence should be enabled by the caller and not here.

There is also another problem in dma_fence_enable_sw_signaling(), it returns early when the fence is already signaled:

        if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
                return;

Please remove that one first.


Why we even need this explicit call if dma_fence_add_callback calls __dma_fence_enable_signaling anyway ?

Two different fence objects.

The dma_fence_add_callback() is done on the hw fence we get in return of submitting the job.

The dma_fence_enable_sw_signaling() here is done on the finished fence we use to signal the completion externally.

Key point is the finished fence should be used by the frontend drivers which uses the scheduler and not by the scheduler itself.

Christian.


Oh, so we need to explicitly call this because dma_fence_add_callback is not always used for finished fence right ?

Yea, then it makes sense that the client needs to manage this since each one has his own logic what to do with it.

Andrey




Andrey



Thanks,
Christian.


+
              r = dma_fence_add_callback(fence, &sched_job->cb,
                             drm_sched_job_done_cb);
              if (r == -ENOENT)





[Index of Archives]     [Linux Input]     [Video for Linux]     [Gstreamer Embedded]     [Mplayer Users]     [Linux USB Devel]     [Linux Audio Users]     [Linux Kernel]     [Linux SCSI]     [Yosemite Backpacking]

  Powered by Linux