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

[Rob Herring]

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>
---
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