On Fri, 28 Aug 2026 21:56:49 +0100 Adrián Larumbe <[email protected]> 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 combined outcome of both of the above was 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. > > 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") Because of how things are currently ordered, this won't be backportable without patch 2, which doesn't have a Fixes tag, so, either we put the fix first, and then we move code, or we make it a single commit. > --- > drivers/gpu/drm/panfrost/panfrost_device.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/drivers/gpu/drm/panfrost/panfrost_device.c > b/drivers/gpu/drm/panfrost/panfrost_device.c > index 99f7da2180f9..70c8109ea698 100644 > --- a/drivers/gpu/drm/panfrost/panfrost_device.c > +++ b/drivers/gpu/drm/panfrost/panfrost_device.c > @@ -322,6 +322,7 @@ int panfrost_device_init(struct panfrost_device *pfdev) > > pm_runtime_set_active(pfdev->base.dev); > pm_runtime_mark_last_busy(pfdev->base.dev); > + pm_runtime_get_noresume(pfdev->base.dev); > pm_runtime_enable(pfdev->base.dev); > pm_runtime_set_autosuspend_delay(pfdev->base.dev, 50); /* ~3 frames */ > pm_runtime_use_autosuspend(pfdev->base.dev); > @@ -334,9 +335,13 @@ int panfrost_device_init(struct panfrost_device *pfdev) > if (err < 0) > goto out_devreg; > > + pm_runtime_put_autosuspend(pfdev->base.dev); > + > return 0; > > out_devreg: > + pm_runtime_dont_use_autosuspend(pfdev->base.dev); > + pm_runtime_put_noidle(pfdev->base.dev); > pm_runtime_disable(pfdev->base.dev); > panfrost_device_disable_hw(pfdev); > panfrost_gem_fini(pfdev); > @@ -363,7 +368,9 @@ int panfrost_device_init(struct panfrost_device *pfdev) > void panfrost_device_fini(struct panfrost_device *pfdev) > { > pm_runtime_get_sync(pfdev->base.dev); > + pm_runtime_dont_use_autosuspend(pfdev->base.dev); > pm_runtime_disable(pfdev->base.dev); > + pm_runtime_put_noidle(pfdev->base.dev); > > panfrost_jm_stop_sched_jobs(pfdev); > panfrost_device_disable_hw(pfdev); >
