On 29/09/2026 04:44, Adrián Larumbe wrote: > During device probe(), failure to do a PM get() will leave the usage_count > set to 0, which is the value assigned at device creation time. That means > when the autosuspend delay expires, runtime suspend callback won't be > invoked, so the device will remain powered on forever. > > On top of that, failure to call PM put() during device unplug means > Panfrost device's PM usage_count increases monotonically for every new > module reload. > > The outcome of both of the above meant that: > > - Devfreq OPP transition notifications would be printed all the time, > even when no jobs are being submitted. This quickly fills the kernel > ring buffer with junk. > - Because MMU interrupts are only enabled when the device is reset, > the very first job targeting the tiler heap BO after device probe() > would always time out, since the driver's PM runtime resume callback > would not be invoked. > > To fix the above: > - Manually adjust the PM refcnt at device probe and removal time. > - Ensure pm_runtime_dont_use_autosuspend is called in the wind-down path. > - Call pm_runtime_put_autosuspend() when device is ready to accept jobs > > Signed-off-by: Adrián Larumbe <[email protected]> > Fixes: 635430797d3f ("drm/panfrost: Rework runtime PM initialization") > Fixes: 876b15d2c88d ("drm/panfrost: Fix module unload")
Reviewed-by: Steven Price <[email protected]> > --- > drivers/gpu/drm/panfrost/panfrost_drv.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c > b/drivers/gpu/drm/panfrost/panfrost_drv.c > index 55fc22e8d4d4..907d4a14a0b5 100644 > --- a/drivers/gpu/drm/panfrost/panfrost_drv.c > +++ b/drivers/gpu/drm/panfrost/panfrost_drv.c > @@ -852,6 +852,11 @@ static int panfrost_probe(struct platform_device *pdev) > goto err_out0; > } > > + /* The reason we must manually set the PM status and usage counter is > + * we have just powered the device up but did not go through the PM > + * runtime resume callback, so we need to update these ourselves. > + */ > + pm_runtime_get_noresume(pfdev->base.dev); > pm_runtime_set_active(pfdev->base.dev); > pm_runtime_mark_last_busy(pfdev->base.dev); > pm_runtime_enable(pfdev->base.dev); > @@ -866,13 +871,16 @@ static int panfrost_probe(struct platform_device *pdev) > if (err < 0) > goto err_out1; > > + pm_runtime_put_autosuspend(pfdev->base.dev); > > return 0; > > err_out1: > + pm_runtime_dont_use_autosuspend(pfdev->base.dev); > pm_runtime_disable(pfdev->base.dev); > panfrost_device_fini(pfdev); > pm_runtime_set_suspended(pfdev->base.dev); > + pm_runtime_put_noidle(pfdev->base.dev); > err_out0: > return err; > } > @@ -884,9 +892,12 @@ static void panfrost_remove(struct platform_device *pdev) > drm_dev_unregister(&pfdev->base); > > pm_runtime_get_sync(pfdev->base.dev); > + pm_runtime_dont_use_autosuspend(pfdev->base.dev); > pm_runtime_disable(pfdev->base.dev); > panfrost_device_fini(pfdev); > pm_runtime_set_suspended(pfdev->base.dev); > + pm_runtime_put_noidle(pfdev->base.dev); > + > } > > static ssize_t profiling_show(struct device *dev, >
