linux-kernel - Re: [PATCH v2 4/5] drm/scheduler: Add fence deadline support

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Message-ID: <e28020c5-3da3-c721-96df-9a115f105bf7@gmail.com>
Date:   Mon, 16 Aug 2021 12:14:35 +0200
From:   Christian König <ckoenig.leichtzumerken@...il.com>
To:     Rob Clark <robdclark@...il.com>, dri-devel@...ts.freedesktop.org
Cc:     linux-arm-msm@...r.kernel.org, freedreno@...ts.freedesktop.org,
        Daniel Vetter <daniel@...ll.ch>,
        Rob Clark <robdclark@...omium.org>,
        David Airlie <airlied@...ux.ie>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Christian König <christian.koenig@....com>,
        Tian Tao <tiantao6@...ilicon.com>,
        Alex Deucher <alexander.deucher@....com>,
        Luben Tuikov <luben.tuikov@....com>,
        Andrey Grodzovsky <andrey.grodzovsky@....com>,
        Steven Price <steven.price@....com>, Roy Sun <Roy.Sun@....com>,
        Lee Jones <lee.jones@...aro.org>,
        Jack Zhang <Jack.Zhang1@....com>,
        open list <linux-kernel@...r.kernel.org>,
        "open list:DMA BUFFER SHARING FRAMEWORK" 
        <linux-media@...r.kernel.org>,
        "moderated list:DMA BUFFER SHARING FRAMEWORK" 
        <linaro-mm-sig@...ts.linaro.org>
Subject: Re: [PATCH v2 4/5] drm/scheduler: Add fence deadline support

Am 07.08.21 um 20:37 schrieb Rob Clark:
> From: Rob Clark <robdclark@...omium.org>
>
> As the finished fence is the one that is exposed to userspace, and
> therefore the one that other operations, like atomic update, would
> block on, we need to propagate the deadline from from the finished
> fence to the actual hw fence.
>
> Signed-off-by: Rob Clark <robdclark@...omium.org>
> ---
>   drivers/gpu/drm/scheduler/sched_fence.c | 25 +++++++++++++++++++++++++
>   drivers/gpu/drm/scheduler/sched_main.c  |  3 +++
>   include/drm/gpu_scheduler.h             |  6 ++++++
>   3 files changed, 34 insertions(+)
>
> diff --git a/drivers/gpu/drm/scheduler/sched_fence.c b/drivers/gpu/drm/scheduler/sched_fence.c
> index 69de2c76731f..f389dca44185 100644
> --- a/drivers/gpu/drm/scheduler/sched_fence.c
> +++ b/drivers/gpu/drm/scheduler/sched_fence.c
> @@ -128,6 +128,30 @@ static void drm_sched_fence_release_finished(struct dma_fence *f)
>   	dma_fence_put(&fence->scheduled);
>   }
>   
> +static void drm_sched_fence_set_deadline_finished(struct dma_fence *f,
> +						  ktime_t deadline)
> +{
> +	struct drm_sched_fence *fence = to_drm_sched_fence(f);
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&fence->lock, flags);
> +
> +	/* If we already have an earlier deadline, keep it: */
> +	if (test_bit(DMA_FENCE_FLAG_HAS_DEADLINE_BIT, &f->flags) &&
> +	    ktime_before(fence->deadline, deadline)) {
> +		spin_unlock_irqrestore(&fence->lock, flags);
> +		return;
> +	}
> +
> +	fence->deadline = deadline;
> +	set_bit(DMA_FENCE_FLAG_HAS_DEADLINE_BIT, &f->flags);
> +
> +	spin_unlock_irqrestore(&fence->lock, flags);
> +
> +	if (fence->parent)
> +		dma_fence_set_deadline(fence->parent, deadline);
> +}
> +
>   static const struct dma_fence_ops drm_sched_fence_ops_scheduled = {
>   	.get_driver_name = drm_sched_fence_get_driver_name,
>   	.get_timeline_name = drm_sched_fence_get_timeline_name,
> @@ -138,6 +162,7 @@ static const struct dma_fence_ops drm_sched_fence_ops_finished = {
>   	.get_driver_name = drm_sched_fence_get_driver_name,
>   	.get_timeline_name = drm_sched_fence_get_timeline_name,
>   	.release = drm_sched_fence_release_finished,
> +	.set_deadline = drm_sched_fence_set_deadline_finished,
>   };
>   
>   struct drm_sched_fence *to_drm_sched_fence(struct dma_fence *f)
> diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
> index a2a953693b45..3ab0900d3596 100644
> --- a/drivers/gpu/drm/scheduler/sched_main.c
> +++ b/drivers/gpu/drm/scheduler/sched_main.c
> @@ -818,6 +818,9 @@ static int drm_sched_main(void *param)
>   
>   		if (!IS_ERR_OR_NULL(fence)) {
>   			s_fence->parent = dma_fence_get(fence);
> +			if (test_bit(DMA_FENCE_FLAG_HAS_DEADLINE_BIT,
> +				     &s_fence->finished.flags))
> +				dma_fence_set_deadline(fence, s_fence->deadline);

Maybe move this into a dma_sched_fence_set_parent() function.

Apart from that looks good to me.

Regards,
Christian.

>   			r = dma_fence_add_callback(fence, &sched_job->cb,
>   						   drm_sched_job_done_cb);
>   			if (r == -ENOENT)
> diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h
> index d18af49fd009..0f08ade614ae 100644
> --- a/include/drm/gpu_scheduler.h
> +++ b/include/drm/gpu_scheduler.h
> @@ -144,6 +144,12 @@ struct drm_sched_fence {
>            */
>   	struct dma_fence		finished;
>   
> +	/**
> +	 * @deadline: deadline set on &drm_sched_fence.finished which
> +	 * potentially needs to be propagated to &drm_sched_fence.parent
> +	 */
> +	ktime_t				deadline;
> +
>           /**
>            * @parent: the fence returned by &drm_sched_backend_ops.run_job
>            * when scheduling the job on hardware. We signal the