linux-kernel - [PATCH v2] drm/panfrost: Sync IRQ by job's timeout handler

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Date:   Sun, 23 Jul 2023 03:01:42 +0300
From:   Dmitry Osipenko <dmitry.osipenko@...labora.com>
To:     Rob Herring <robh@...nel.org>, Steven Price <steven.price@....com>,
        Boris Brezillon <boris.brezillon@...labora.com>
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        kernel@...labora.com
Subject: [PATCH v2] drm/panfrost: Sync IRQ by job's timeout handler

Panfrost IRQ handler may stuck for a long time, for example this happens
when there is a bad HDMI connection and HDMI handler takes a long time to
finish processing, holding Panfrost. Make Panfrost's job timeout handler
to sync IRQ before checking fence signal status in order to prevent
spurious job timeouts due to a slow IRQ processing.

Signed-off-by: Dmitry Osipenko <dmitry.osipenko@...labora.com>
---

Changelog:

v2: - Moved synchronize_irq() after first signal-check to avoid unnecessary
      blocking on syncing.

    - Added warn message about high interrupt latency.

 drivers/gpu/drm/panfrost/panfrost_job.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c
index dbc597ab46fb..a7663d7847a2 100644
--- a/drivers/gpu/drm/panfrost/panfrost_job.c
+++ b/drivers/gpu/drm/panfrost/panfrost_job.c
@@ -720,6 +720,13 @@ static enum drm_gpu_sched_stat panfrost_job_timedout(struct drm_sched_job
 	if (dma_fence_is_signaled(job->done_fence))
 		return DRM_GPU_SCHED_STAT_NOMINAL;
 
+	synchronize_irq(pfdev->js->irq);
+
+	if (dma_fence_is_signaled(job->done_fence)) {
+		dev_warn(pfdev->dev, "unexpectedly high interrupt latency\n");
+		return DRM_GPU_SCHED_STAT_NOMINAL;
+	}
+
 	dev_err(pfdev->dev, "gpu sched timeout, js=%d, config=0x%x, status=0x%x, head=0x%x, tail=0x%x, sched_job=%p",
 		js,
 		job_read(pfdev, JS_CONFIG(js)),
-- 
2.41.0