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.

Reviewed-by: Steven Price <steven.price@arm.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Tested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> # MediaTek MT8192 and MT8195 Chromebooks
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230807000444.14926-1-dmitry.osipenko@collabora.com

diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c
index dbc597a..a8b4827 100644 (file)
--- a/drivers/gpu/drm/panfrost/panfrost_job.c
+++ b/drivers/gpu/drm/panfrost/panfrost_job.c
@@ -720,6 +720,22 @@ 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;
 
+       /*
+        * Panfrost IRQ handler may take a long time to process an interrupt
+        * if there is another IRQ handler hogging the processing.
+        * For example, the HDMI encoder driver might be stuck in the IRQ
+        * handler for a significant time in a case of bad cable connection.
+        * In order to catch such cases and not report spurious Panfrost
+        * job timeouts, synchronize the IRQ handler and re-check the fence
+        * status.
+        */
+       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)),