[PATCH v14 10/15] drm/panfrost: Add debugfs knob for manually triggering a GPU reset

[Adrián Larumbe]

This will be of great help when testing potential races between the GPU
reset sequence and other parts of the code accessing HW registers.

We must also disable the reset work item rather than simply cancelling
it, to prevent the knob from triggering another reset when the device
is being removed.

At the moment, the only legitimate input value for the knob is '1'. This is
to allow for future inputs that would encode alternative reset scenarios
we'd want to trigger manually.

Reviewed-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
Reviewed-by: Steven Price <steven.price@xxxxxxx>
Signed-off-by: Adrián Larumbe <adrian.larumbe@xxxxxxxxxxxxx>
---
 drivers/gpu/drm/panfrost/panfrost_device.c | 46 ++++++++++++++++++++++++++++++
 drivers/gpu/drm/panfrost/panfrost_job.c    |  2 +-
 2 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/panfrost/panfrost_device.c b/drivers/gpu/drm/panfrost/panfrost_device.c
index 687230225743..b3dae6ce3eb0 100644
--- a/drivers/gpu/drm/panfrost/panfrost_device.c
+++ b/drivers/gpu/drm/panfrost/panfrost_device.c
@@ -2,6 +2,7 @@
 /* Copyright 2018 Marty E. Plummer <hanetzer@xxxxxxxxxxxxx> */
 /* Copyright 2019 Linaro, Ltd, Rob Herring <robh@xxxxxxxxxx> */
 
+#include <linux/debugfs.h>
 #include <linux/clk.h>
 #include <linux/reset.h>
 #include <linux/platform_device.h>
@@ -623,9 +624,54 @@ EXPORT_GPL_DEV_PM_OPS(panfrost_pm_ops) = {
 };
 
 #ifdef CONFIG_DEBUG_FS
+static int reset_get(void *data, u64 *val)
+{
+	struct panfrost_device *pfdev =
+		container_of(data, struct panfrost_device, base);
+
+	*val = atomic_read(&pfdev->reset.pending);
+	return 0;
+}
+
+static int reset_set(void *data, u64 val)
+{
+	struct panfrost_device *pfdev =
+		container_of(data, struct panfrost_device, base);
+	int ret;
+
+	if (val != 1)
+		return -EINVAL;
+
+	ret = pm_runtime_get_if_active(pfdev->base.dev);
+	if (!ret)
+		return 0;
+
+	panfrost_device_schedule_reset(pfdev);
+	flush_work(&pfdev->reset.work);
+
+	/* ret < 0 means runtime PM for the device is disabled, so we
+	 * only need to return the PM reference in the opposite case
+	 */
+	if (ret > 0)
+		pm_runtime_put(pfdev->base.dev);
+
+	return 0;
+}
+
+DEFINE_DEBUGFS_ATTRIBUTE(panfrost_reset_debugfs_fops,
+			 reset_get, reset_set,
+			 "0x%08llx\n");
+
+static void panfrost_reset_debugfs_init(struct drm_minor *minor)
+{
+	debugfs_create_file("reset", 0600, minor->debugfs_root,
+			    minor->dev, &panfrost_reset_debugfs_fops);
+}
+
 void panfrost_device_debugfs_init(struct drm_minor *minor)
 {
 	panfrost_gem_debugfs_init(minor);
 	panfrost_sched_debugfs_init(minor);
+	panfrost_reset_debugfs_init(minor);
 }
 #endif // CONFIG_DEBUG_FS
diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c
index 00fb36c577df..ab65786bf63b 100644
--- a/drivers/gpu/drm/panfrost/panfrost_job.c
+++ b/drivers/gpu/drm/panfrost/panfrost_job.c
@@ -932,7 +932,7 @@ void panfrost_jm_fini(struct panfrost_device *pfdev)
 		drm_sched_fini(&js->queue[j].sched);
 	}
 
-	cancel_work_sync(&pfdev->reset.work);
+	disable_work_sync(&pfdev->reset.work);
 	destroy_workqueue(pfdev->reset.wq);
 }
 

-- 
2.55.0