Re: [PATCH v5 07/11] drm/panfrost: Add debugfs knob for manually triggering a GPU reset

[Boris Brezillon]

On Tue, 11 Aug 2026 22:42:16 +0100
Adrián Larumbe <adrian.larumbe@xxxxxxxxxxxxx> wrote:

> This will be of great help when testing potential races between the GPU
> reset sequence and other parts of the code accessing HW registers.
> 
> Signed-off-by: Adrián Larumbe <adrian.larumbe@xxxxxxxxxxxxx>
> ---
>  drivers/gpu/drm/panfrost/panfrost_device.c | 39 ++++++++++++++++++++++++++++++
>  drivers/gpu/drm/panfrost/panfrost_device.h |  3 +++
>  drivers/gpu/drm/panfrost/panfrost_drv.c    |  1 +
>  3 files changed, 43 insertions(+)
> 
> diff --git a/drivers/gpu/drm/panfrost/panfrost_device.c b/drivers/gpu/drm/panfrost/panfrost_device.c
> index 52f4b8c6a05f..5b66173c75b9 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>
> @@ -608,3 +609,41 @@ void panfrost_device_reset(struct panfrost_device *pfdev, bool enable_job_int)
>  	if (enable_job_int)
>  		panfrost_jm_enable_interrupts(pfdev);
>  }
> +
> +#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;
> +
> +	ret = pm_runtime_get_if_in_use(pfdev->base.dev);
> +
> +	if (ret > 0) {
> +		panfrost_device_schedule_reset(pfdev);
> +		flush_work(&pfdev->reset.work);
> +		pm_runtime_put(pfdev->base.dev);
> +	}
> +
> +	return 0;
> +}
> +
> +DEFINE_DEBUGFS_ATTRIBUTE(panfrost_reset_debugfs_fops,
> +			 reset_get, reset_set,
> +			 "0x%08llx\n");
> +
> +void panfrost_reset_debugfs_init(struct drm_minor *minor)
> +{
> +	debugfs_create_file("reset", 0600, minor->debugfs_root,
> +			    minor->dev, &panfrost_reset_debugfs_fops);
> +}
> +#endif // CONFIG_DEBUG_FS
> diff --git a/drivers/gpu/drm/panfrost/panfrost_device.h b/drivers/gpu/drm/panfrost/panfrost_device.h
> index 0fd33bc5b86f..4bbaaaf827a5 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_device.h
> +++ b/drivers/gpu/drm/panfrost/panfrost_device.h
> @@ -350,4 +350,7 @@ panfrost_device_started(struct panfrost_device *pfdev)
>  	return pfdev->js;
>  }
>  
> +#ifdef CONFIG_DEBUG_FS
> +void panfrost_reset_debugfs_init(struct drm_minor *minor);
> +#endif // CONFIG_DEBUG_FS
>  #endif
> diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/panfrost/panfrost_drv.c
> index 8410de95e364..958f1d36ab10 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_drv.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
> @@ -916,6 +916,7 @@ static void panfrost_debugfs_init(struct drm_minor *minor)
>  {
>  	panthor_gems_debugfs_init(minor);
>  	panfrost_sched_debugfs_init(minor);
> +	panfrost_reset_debugfs_init(minor);

Nit: I'd probably go for panfrost_device_debugfs_init(), and since gems
and sched are sub-components of the device, I'd call the other
panfrost_{gems,sched}_debugfs_init() helpers from
panfrost_device_debugfs_init().

>  }
>  #endif
>  
>