Re: [PATCH v7 11/17] drm/panfrost: Add debugfs knob for manually triggering a GPU reset

[Adrián Larumbe]

On 01.09.2026 15:27, Boris Brezillon wrote:
> On Fri, 28 Aug 2026 21:56:51 +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 | 35 ++++++++++++++++++++++++++++++
> >  1 file changed, 35 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/panfrost/panfrost_device.c b/drivers/gpu/drm/panfrost/panfrost_device.c
> > index d8acae9b8cfa..b6a48ae0d3a6 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>
> > @@ -600,9 +601,43 @@ 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);
> > +
> > +	if (pm_runtime_get_if_in_use(pfdev->base.dev)) {
> 
> Are you sure it's not pm_runtime_get_if_active() we want here? If use
> the _if_in_use() variant and autosuspend is enabled, we might skip a
> reset on a device that's active.

Do you mean if a driver has brought the RPM count down to 0 and scheduled a deferred suspend?
Couldn't manually triggering a reset then somehow race with whatever is being done in
panfrost_device_runtime_suspend() ?

> > +		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");
> > +
> > +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_gems_debugfs_init(minor);
> >  	panfrost_sched_debugfs_init(minor);
> > +	panfrost_reset_debugfs_init(minor);
> >  }
> >  #endif // CONFIG_DEBUG_FS
> > 

Adrian Larumbe