[Intel-gfx] [PATCH 3/9] drm/i915: Add i915_sched_engine_reset_on_empty function

[Jason Ekstrand]

On Thu, Jun 3, 2021 at 4:09 PM Matthew Brost <matthew.brost at intel.com> wrote:
>
> Rather than touching schedule state in the generic PM code, reset the
> priolist allocation when empty in the submission code. Add a wrapper
> function to do this and update the backends to call it in the correct
> place.

Seems reasonable, I think.  I'm by no means an expert but

Reviewed-by: Jason Ekstrand <jason at jlekstrand.net>

anyway.  My one suggestion would be to tweak the commit message to
talk about the functional change rather than the helper.  Something
like

drm/i915: Reset sched_engine.no_priolist immediately after dequeue

Typically patches which say "add a helper function" don't come with a
non-trivial functional change.

--Jason


> Signed-off-by: Matthew Brost <matthew.brost at intel.com>
> ---
>  drivers/gpu/drm/i915/gt/intel_engine_pm.c            | 2 --
>  drivers/gpu/drm/i915/gt/intel_execlists_submission.c | 1 +
>  drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c    | 2 ++
>  drivers/gpu/drm/i915/i915_scheduler.h                | 7 +++++++
>  4 files changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_pm.c b/drivers/gpu/drm/i915/gt/intel_engine_pm.c
> index b6a00dd72808..1f07ac4e0672 100644
> --- a/drivers/gpu/drm/i915/gt/intel_engine_pm.c
> +++ b/drivers/gpu/drm/i915/gt/intel_engine_pm.c
> @@ -280,8 +280,6 @@ static int __engine_park(struct intel_wakeref *wf)
>         if (engine->park)
>                 engine->park(engine);
>
> -       engine->sched_engine->no_priolist = false;
> -
>         /* While gt calls i915_vma_parked(), we have to break the lock cycle */
>         intel_gt_pm_put_async(engine->gt);
>         return 0;
> diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> index 2326a73af6d3..609753b5401a 100644
> --- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> +++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> @@ -1553,6 +1553,7 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
>          * interrupt for secondary ports).
>          */
>         sched_engine->queue_priority_hint = queue_prio(sched_engine);
> +       i915_sched_engine_reset_on_empty(sched_engine);
>         spin_unlock(&engine->active.lock);
>
>         /*
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> index 5d00f2e3c1de..f4a6fbfaf82e 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> @@ -263,6 +263,8 @@ static void guc_submission_tasklet(struct tasklet_struct *t)
>
>         __guc_dequeue(engine);
>
> +       i915_sched_engine_reset_on_empty(engine->sched_engine);
> +
>         spin_unlock_irqrestore(&engine->active.lock, flags);
>  }
>
> diff --git a/drivers/gpu/drm/i915/i915_scheduler.h b/drivers/gpu/drm/i915/i915_scheduler.h
> index 5bec7b3b8456..713c38c99de9 100644
> --- a/drivers/gpu/drm/i915/i915_scheduler.h
> +++ b/drivers/gpu/drm/i915/i915_scheduler.h
> @@ -72,6 +72,13 @@ i915_sched_engine_is_empty(struct i915_sched_engine *sched_engine)
>         return RB_EMPTY_ROOT(&sched_engine->queue.rb_root);
>  }
>
> +static inline void
> +i915_sched_engine_reset_on_empty(struct i915_sched_engine *sched_engine)
> +{
> +       if (i915_sched_engine_is_empty(sched_engine))
> +               sched_engine->no_priolist = false;
> +}
> +
>  void i915_request_show_with_schedule(struct drm_printer *m,
>                                      const struct i915_request *rq,
>                                      const char *prefix,
> --
> 2.28.0
>
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