[PATCH 2/8] drm/amdgpu: rework queue reset scheduler interaction

[Alex Deucher]

On Mon, May 19, 2025 at 2:30 PM Alex Deucher <alexander.deucher at amd.com> wrote:
>
> From: Christian König <ckoenig.leichtzumerken at gmail.com>
>
> Stopping the scheduler for queue reset is generally a good idea because
> it prevents any worker from touching the ring buffer.
>
> But using amdgpu_fence_driver_force_completion() before restarting it was
> a really bad idea because it marked fences as failed while the work was
> potentially still running.
>
> Stop doing that and cleanup the comment a bit.
>
> Signed-off-by: Christian König <christian.koenig at amd.com>
> Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_job.c | 27 ++++++++++++-------------
>  1 file changed, 13 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
> index acb21fc8b3ce5..a0fab947143b5 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
> @@ -136,10 +136,12 @@ static enum drm_gpu_sched_stat amdgpu_job_timedout(struct drm_sched_job *s_job)
>         } else if (amdgpu_gpu_recovery && ring->funcs->reset) {
>                 bool is_guilty;
>
> -               dev_err(adev->dev, "Starting %s ring reset\n", s_job->sched->name);
> -               /* stop the scheduler, but don't mess with the
> -                * bad job yet because if ring reset fails
> -                * we'll fall back to full GPU reset.
> +               dev_err(adev->dev, "Starting %s ring reset\n",
> +                       s_job->sched->name);
> +
> +               /*
> +                * Stop the scheduler to prevent anybody else from touching the
> +                * ring buffer.
>                  */
>                 drm_sched_wqueue_stop(&ring->sched);
>
> @@ -157,19 +159,16 @@ static enum drm_gpu_sched_stat amdgpu_job_timedout(struct drm_sched_job *s_job)
>
>                 r = amdgpu_ring_reset(ring, job->vmid);
>                 if (!r) {
> -                       if (amdgpu_ring_sched_ready(ring))
> -                               drm_sched_stop(&ring->sched, s_job);
> -                       if (is_guilty) {
> +                       if (is_guilty)
>                                 atomic_inc(&ring->adev->gpu_reset_counter);
> -                               amdgpu_fence_driver_force_completion(ring);

Do we still need this in the case of rings where we reset the entire
queue?  E.g., compute or VCN?  In which case we should move this to
the ring->reset callback.

Alex

> -                       }
> -                       if (amdgpu_ring_sched_ready(ring))
> -                               drm_sched_start(&ring->sched, 0);
> -                       dev_err(adev->dev, "Ring %s reset succeeded\n", ring->sched.name);
> -                       drm_dev_wedged_event(adev_to_drm(adev), DRM_WEDGE_RECOVERY_NONE);
> +                       drm_sched_wqueue_start(&ring->sched);
> +                       dev_err(adev->dev, "Ring %s reset succeeded\n",
> +                               ring->sched.name);
> +                       drm_dev_wedged_event(adev_to_drm(adev),
> +                                            DRM_WEDGE_RECOVERY_NONE);
>                         goto exit;
>                 }
> -               dev_err(adev->dev, "Ring %s reset failure\n", ring->sched.name);
> +               dev_err(adev->dev, "Ring %s reset failed\n", ring->sched.name);
>         }
>         dma_fence_set_error(&s_job->s_fence->finished, -ETIME);
>
> --
> 2.49.0
>