linux-kernel - [PATCH] drm/panfrost: Fix inbalance of devfreq record

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Message-Id: <20200522153653.40754-1-steven.price@arm.com>
Date:   Fri, 22 May 2020 16:36:53 +0100
From:   Steven Price <steven.price@....com>
To:     Rob Herring <robh@...nel.org>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>
Cc:     Daniel Vetter <daniel@...ll.ch>, David Airlie <airlied@...ux.ie>,
        Alyssa Rosenzweig <alyssa.rosenzweig@...labora.com>,
        Steven Price <steven.price@....com>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: [PATCH] drm/panfrost: Fix inbalance of devfreq record_busy/idle()

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@....com>
---
 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