[PATCH v3 2/8] drm/panfrost: Hold runtime PM reference until jobs complete

[Steven Price]

On 26/08/2019 23:33, Rob Herring wrote:
> Doing a pm_runtime_put as soon as a job is submitted is wrong as it should
> not happen until the job completes. It works currently because we are
> relying on the autosuspend timeout to keep the h/w enabled.
> 
> Fixes: f3ba91228e8e ("drm/panfrost: Add initial panfrost driver")
> Cc: Tomeu Vizoso <tomeu.vizoso at collabora.com>
> Cc: Steven Price <steven.price at arm.com>
> Cc: Alyssa Rosenzweig <alyssa.rosenzweig at collabora.com>
> Cc: David Airlie <airlied at linux.ie>
> Cc: Daniel Vetter <daniel at ffwll.ch>
> Signed-off-by: Rob Herring <robh at kernel.org>

Reviewed-by: Steven Price <steven.price at arm.com>

Steve

> ---
> v3:
>  - Fix race between clearing pfdev->jobs[] in timeout and the ISR using the job_lock
>  - Maintain pm_runtime_put in the panfrost_job_hw_submit error path
> 
>  drivers/gpu/drm/panfrost/panfrost_job.c | 39 ++++++++++++++++++-------
>  1 file changed, 28 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c
> index 05c85f45a0de..18bcc9bac6d2 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_job.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_job.c
> @@ -150,8 +150,10 @@ static void panfrost_job_hw_submit(struct panfrost_job *job, int js)
>  	if (ret < 0)
>  		return;
> 
> -	if (WARN_ON(job_read(pfdev, JS_COMMAND_NEXT(js))))
> -		goto end;
> +	if (WARN_ON(job_read(pfdev, JS_COMMAND_NEXT(js)))) {
> +		pm_runtime_put_sync_autosuspend(pfdev->dev);
> +		return;
> +	}
> 
>  	cfg = panfrost_mmu_as_get(pfdev, &job->file_priv->mmu);
> 
> @@ -187,10 +189,6 @@ static void panfrost_job_hw_submit(struct panfrost_job *job, int js)
>  	job_write(pfdev, JS_COMMAND_NEXT(js), JS_COMMAND_START);
> 
>  	spin_unlock_irqrestore(&pfdev->hwaccess_lock, flags);
> -
> -end:
> -	pm_runtime_mark_last_busy(pfdev->dev);
> -	pm_runtime_put_autosuspend(pfdev->dev);
>  }
> 
>  static void panfrost_acquire_object_fences(struct drm_gem_object **bos,
> @@ -369,6 +367,7 @@ static void panfrost_job_timedout(struct drm_sched_job *sched_job)
>  	struct panfrost_job *job = to_panfrost_job(sched_job);
>  	struct panfrost_device *pfdev = job->pfdev;
>  	int js = panfrost_job_get_slot(job);
> +	unsigned long flags;
>  	int i;
> 
>  	/*
> @@ -394,6 +393,15 @@ static void panfrost_job_timedout(struct drm_sched_job *sched_job)
>  	if (sched_job)
>  		drm_sched_increase_karma(sched_job);
> 
> +	spin_lock_irqsave(&pfdev->js->job_lock, flags);
> +	for (i = 0; i < NUM_JOB_SLOTS; i++) {
> +		if (pfdev->jobs[i]) {
> +			pm_runtime_put_noidle(pfdev->dev);
> +			pfdev->jobs[i] = NULL;
> +		}
> +	}
> +	spin_unlock_irqrestore(&pfdev->js->job_lock, flags);
> +
>  	/* panfrost_core_dump(pfdev); */
> 
>  	panfrost_devfreq_record_transition(pfdev, js);
> @@ -450,12 +458,21 @@ static irqreturn_t panfrost_job_irq_handler(int irq, void *data)
>  		}
> 
>  		if (status & JOB_INT_MASK_DONE(j)) {
> -			struct panfrost_job *job = pfdev->jobs[j];
> +			struct panfrost_job *job;
> +
> +			spin_lock(&pfdev->js->job_lock);
> +			job = pfdev->jobs[j];
> +			/* Only NULL if job timeout occurred */
> +			if (job) {
> +				pfdev->jobs[j] = NULL;
> +
> +				panfrost_mmu_as_put(pfdev, &job->file_priv->mmu);
> +				panfrost_devfreq_record_transition(pfdev, j);
> 
> -			pfdev->jobs[j] = NULL;
> -			panfrost_mmu_as_put(pfdev, &job->file_priv->mmu);
> -			panfrost_devfreq_record_transition(pfdev, j);
> -			dma_fence_signal(job->done_fence);
> +				dma_fence_signal_locked(job->done_fence);
> +				pm_runtime_put_autosuspend(pfdev->dev);
> +			}
> +			spin_unlock(&pfdev->js->job_lock);
>  		}
> 
>  		status &= ~mask;
> --
> 2.20.1
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