Re: [PATCH] drm/panfrost: Fix inbalance of devfreq record_busy/idle()

From: Alyssa Rosenzweig
Date: Fri May 22 2020 - 13:13:30 EST


A-b

On Fri, May 22, 2020 at 04:36:53PM +0100, Steven Price wrote:
> The calls to panfrost_devfreq_record_busy() and
> panfrost_devfreq_record_idle() must be balanced to ensure that the
> devfreq utilisation is correctly reported. But there are two cases where
> this doesn't work correctly.
>
> In panfrost_job_hw_submit() if pm_runtime_get_sync() fails or the
> WARN_ON() fires then no call to panfrost_devfreq_record_busy() is made,
> but when the job times out the corresponding _record_idle() call is
> still made in panfrost_job_timedout(). Move the call up to ensure that
> it always happens.
>
> Secondly panfrost_job_timedout() only makes a single call to
> panfrost_devfreq_record_idle() even if it is cleaning up multiple jobs.
> Move the call inside the loop to ensure that the number of
> _record_idle() calls matches the number of _record_busy() calls.
>
> Fixes: 9e62b885f715 ("drm/panfrost: Simplify devfreq utilisation tracking")
> Signed-off-by: Steven Price <steven.price@xxxxxxx>
> ---
> drivers/gpu/drm/panfrost/panfrost_job.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c
> index b2f09c038d35..ac87ef675e8a 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_job.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_job.c
> @@ -145,6 +145,8 @@ static void panfrost_job_hw_submit(struct panfrost_job *job, int js)
> u64 jc_head = job->jc;
> int ret;
>
> + panfrost_devfreq_record_busy(pfdev);
> +
> ret = pm_runtime_get_sync(pfdev->dev);
> if (ret < 0)
> return;
> @@ -155,7 +157,6 @@ static void panfrost_job_hw_submit(struct panfrost_job *job, int js)
> }
>
> cfg = panfrost_mmu_as_get(pfdev, &job->file_priv->mmu);
> - panfrost_devfreq_record_busy(pfdev);
>
> job_write(pfdev, JS_HEAD_NEXT_LO(js), jc_head & 0xFFFFFFFF);
> job_write(pfdev, JS_HEAD_NEXT_HI(js), jc_head >> 32);
> @@ -410,12 +411,12 @@ static void panfrost_job_timedout(struct drm_sched_job *sched_job)
> for (i = 0; i < NUM_JOB_SLOTS; i++) {
> if (pfdev->jobs[i]) {
> pm_runtime_put_noidle(pfdev->dev);
> + panfrost_devfreq_record_idle(pfdev);
> pfdev->jobs[i] = NULL;
> }
> }
> spin_unlock_irqrestore(&pfdev->js->job_lock, flags);
>
> - panfrost_devfreq_record_idle(pfdev);
> panfrost_device_reset(pfdev);
>
> for (i = 0; i < NUM_JOB_SLOTS; i++)
> --
> 2.20.1
>