Re: [PATCH v3 08/15] drm/panfrost: Use a threaded IRQ for job interrupts

On 25/06/2021 14:33, Boris Brezillon wrote:

This should avoid switching to interrupt context when the GPU is under heavy use.

v3:

• Don't take the job_lock in panfrost_job_handle_irq()

Signed-off-by: Boris Brezillon boris.brezillon@collabora.com

Reviewed-by: Steven Price steven.price@arm.com

---

drivers/gpu/drm/panfrost/panfrost_job.c | 53 ++++++++++++++++++------- 1 file changed, 38 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c index be8f68f63974..e0c479e67304 100644 --- a/drivers/gpu/drm/panfrost/panfrost_job.c +++ b/drivers/gpu/drm/panfrost/panfrost_job.c @@ -470,19 +470,12 @@ static const struct drm_sched_backend_ops panfrost_sched_ops = { .free_job = panfrost_job_free };

-static irqreturn_t panfrost_job_irq_handler(int irq, void *data) +static void panfrost_job_handle_irq(struct panfrost_device *pfdev, u32 status) {

• struct panfrost_device *pfdev = data;

• u32 status = job_read(pfdev, JOB_INT_STAT); int j;

  dev_dbg(pfdev->dev, "jobslot irq status=%x\n", status);

• if (!status)

• return IRQ_NONE;
  

• pm_runtime_mark_last_busy(pfdev->dev);

• for (j = 0; status; j++) { u32 mask = MK_JS_MASK(j);

@@ -519,7 +512,6 @@ static irqreturn_t panfrost_job_irq_handler(int irq, void *data) if (status & JOB_INT_MASK_DONE(j)) { struct panfrost_job *job;

• 	spin_lock(&pfdev->js->job_lock);
  job = pfdev->jobs[j];
  /* Only NULL if job timeout occurred */
  if (job) {
  

@@ -531,21 +523,49 @@ static irqreturn_t panfrost_job_irq_handler(int irq, void *data) dma_fence_signal_locked(job->done_fence); pm_runtime_put_autosuspend(pfdev->dev); }

• 	spin_unlock(&pfdev->js->job_lock);
  

  }

  status &= ~mask; }

+}

+static irqreturn_t panfrost_job_irq_handler_thread(int irq, void *data) +{

• struct panfrost_device *pfdev = data;
• u32 status = job_read(pfdev, JOB_INT_RAWSTAT);
• while (status) {

• pm_runtime_mark_last_busy(pfdev->dev);
  

• spin_lock(&pfdev->js->job_lock);
  

• panfrost_job_handle_irq(pfdev, status);
  

• spin_unlock(&pfdev->js->job_lock);
  

• status = job_read(pfdev, JOB_INT_RAWSTAT);
  

• }
• job_write(pfdev, JOB_INT_MASK,

•   GENMASK(16 + NUM_JOB_SLOTS - 1, 16) |
  

•   GENMASK(NUM_JOB_SLOTS - 1, 0));
  

  return IRQ_HANDLED;

}

+static irqreturn_t panfrost_job_irq_handler(int irq, void *data) +{

• struct panfrost_device *pfdev = data;
• u32 status = job_read(pfdev, JOB_INT_STAT);
• if (!status)

• return IRQ_NONE;
  

• job_write(pfdev, JOB_INT_MASK, 0);
• return IRQ_WAKE_THREAD;

+}

static void panfrost_reset(struct work_struct *work) { struct panfrost_device *pfdev = container_of(work, struct panfrost_device, reset.work);

• unsigned long flags; unsigned int i; bool cookie;

@@ -575,7 +595,7 @@ static void panfrost_reset(struct work_struct *work) /* All timers have been stopped, we can safely reset the pending state. */ atomic_set(&pfdev->reset.pending, 0);

• spin_lock_irqsave(&pfdev->js->job_lock, flags);

• spin_lock(&pfdev->js->job_lock); for (i = 0; i < NUM_JOB_SLOTS; i++) { if (pfdev->jobs[i]) { pm_runtime_put_noidle(pfdev->dev);

@@ -583,7 +603,7 @@ static void panfrost_reset(struct work_struct *work) pfdev->jobs[i] = NULL; } }

• spin_unlock_irqrestore(&pfdev->js->job_lock, flags);

• spin_unlock(&pfdev->js->job_lock);

  panfrost_device_reset(pfdev);

@@ -610,8 +630,11 @@ int panfrost_job_init(struct panfrost_device *pfdev) if (irq <= 0) return -ENODEV;

• ret = devm_request_irq(pfdev->dev, irq, panfrost_job_irq_handler,

• 	       IRQF_SHARED, KBUILD_MODNAME "-job", pfdev);
  

• ret = devm_request_threaded_irq(pfdev->dev, irq,

• 			panfrost_job_irq_handler,
  

• 			panfrost_job_irq_handler_thread,
  

• 			IRQF_SHARED, KBUILD_MODNAME "-job",
  

• 			pfdev);
  

  if (ret) { dev_err(pfdev->dev, "failed to request job irq"); return ret;