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

["Adrián Larumbe" <adrian.larumbe@collabora.com>]

On 12.08.2026 11:17, Boris Brezillon wrote:
> On Tue, 11 Aug 2026 22:42:16 +0100
> Adrián Larumbe <adrian.larumbe@collabora.com> 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@collabora.com>
> > ---
> >  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@startmail.com> */
> >  /* Copyright 2019 Linaro, Ltd, Rob Herring <robh@kernel.org> */
> >  
> > +#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().

Acked, will do for the next iteration. Also, I noticed there's quite a bit of debugfs stuff
in panfrost_drv.c. I should probably move it all under the relevant subsystem file and make
the debugfs init functions available to panfrost_drv.c

> >  }
> >  #endif
> >  
> >