Re: [PATCH 2/6] thermal: of: Export non-devres helper to register/unregister thermal zone

Ulf Hansson
2025-01-15T15:43:17Z

On Thu, 9 Jan 2025 at 18:34, Daniel Lezcano <daniel.lezcano@linaro.org> wrote:
>
>
> Ulf,
>
> can you have a look at this particular patch please ?
>
> Perhaps this scenario already happened in the past and there is an
> alternative to fix it instead of this proposed change

I think the patch makes sense.

If there is a PM domain that is attached to the device that is
managing the clocks for the thermal zone, the detach procedure
certainly needs to be well controlled/synchronized.

>
>
> On 03/01/2025 17:38, Claudiu wrote:
> > From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
> >
> > On the Renesas RZ/G3S (and other Renesas SoCs, e.g., RZ/G2{L, LC, UL}),
> > clocks are managed through PM domains. These PM domains, registered on
> > behalf of the clock controller driver, are configured with
> > GENPD_FLAG_PM_CLK. In most of the Renesas drivers used by RZ SoCs, the
> > clocks are enabled/disabled using runtime PM APIs.
> >
> > During probe, devices are attached to the PM domain controlling their
> > clocks. Similarly, during removal, devices are detached from the PM domain.
> >
> > The detachment call stack is as follows:
> >
> > device_driver_detach() ->
> > device_release_driver_internal() ->
> > __device_release_driver() ->
> > device_remove() ->
> > platform_remove() ->
> > dev_pm_domain_detach()
> >
> > In the upcoming Renesas RZ/G3S thermal driver, the
> > struct thermal_zone_device_ops::change_mode API is implemented to
> > start/stop the thermal sensor unit. Register settings are updated within
> > the change_mode API.
> >
> > In case devres helpers are used for thermal zone register/unregister the
> > struct thermal_zone_device_ops::change_mode API is invoked when the
> > driver is unbound. The identified call stack is as follows:
> >
> > device_driver_detach() ->
> > device_release_driver_internal() ->
> > device_unbind_cleanup() ->
> > devres_release_all() ->
> > devm_thermal_of_zone_release() ->
> > thermal_zone_device_disable() ->
> > thermal_zone_device_set_mode() ->
> > rzg3s_thermal_change_mode()
> >
> > The device_unbind_cleanup() function is called after the thermal device is
> > detached from the PM domain (via dev_pm_domain_detach()).
> >
> > The rzg3s_thermal_change_mode() implementation calls
> > pm_runtime_resume_and_get()/pm_runtime_put_autosuspend() before/after
> > accessing the registers. However, during the unbind scenario, the
> > devm_thermal_of_zone_release() is invoked after dev_pm_domain_detach().
> > Consequently, the clocks are not enabled, as the device is removed from
> > the PM domain at this time, leading to an Asynchronous SError Interrupt.
> > The system cannot be used after this.
> >
> > Add thermal_of_zone_register()/thermal_of_zone_unregister(). These will
> > be used in the upcomming RZ/G3S thermal driver.
> >
> > Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>

Kind regards
Uffe

> > ---
> > drivers/thermal/thermal_of.c | 8 +++++---
> > include/linux/thermal.h | 14 ++++++++++++++
> > 2 files changed, 19 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/thermal/thermal_of.c b/drivers/thermal/thermal_of.c
> > index fab11b98ca49..8fc35d20db60 100644
> > --- a/drivers/thermal/thermal_of.c
> > +++ b/drivers/thermal/thermal_of.c
> > @@ -329,11 +329,12 @@ static bool thermal_of_should_bind(struct thermal_zone_device *tz,
> > *
> > * @tz: a pointer to the thermal zone structure
> > */
> > -static void thermal_of_zone_unregister(struct thermal_zone_device *tz)
> > +void thermal_of_zone_unregister(struct thermal_zone_device *tz)
> > {
> > thermal_zone_device_disable(tz);
> > thermal_zone_device_unregister(tz);
> > }
> > +EXPORT_SYMBOL_GPL(thermal_of_zone_unregister);
> >
> > /**
> > * thermal_of_zone_register - Register a thermal zone with device node
> > @@ -355,8 +356,8 @@ static void thermal_of_zone_unregister(struct thermal_zone_device *tz)
> > * - ENOMEM: if one structure can not be allocated
> > * - Other negative errors are returned by the underlying called functions
> > */
> > -static struct thermal_zone_device *thermal_of_zone_register(struct device_node *sensor, int id, void *data,
> > - const struct thermal_zone_device_ops *ops)
> > +struct thermal_zone_device *thermal_of_zone_register(struct device_node *sensor, int id, void *data,
> > + const struct thermal_zone_device_ops *ops)
> > {
> > struct thermal_zone_device_ops of_ops = *ops;
> > struct thermal_zone_device *tz;
> > @@ -429,6 +430,7 @@ static struct thermal_zone_device *thermal_of_zone_register(struct device_node *
> >
> > return ERR_PTR(ret);
> > }
> > +EXPORT_SYMBOL_GPL(thermal_of_zone_register);
> >
> > static void devm_thermal_of_zone_release(struct device *dev, void *res)
> > {
> > diff --git a/include/linux/thermal.h b/include/linux/thermal.h
> > index 69f9bedd0ee8..adbb4092a064 100644
> > --- a/include/linux/thermal.h
> > +++ b/include/linux/thermal.h
> > @@ -195,13 +195,23 @@ struct thermal_zone_params {
> >
> > /* Function declarations */
> > #ifdef CONFIG_THERMAL_OF
> > +struct thermal_zone_device *thermal_of_zone_register(struct device_node *sensor, int id, void *data,
> > + const struct thermal_zone_device_ops *ops);
> > struct thermal_zone_device *devm_thermal_of_zone_register(struct device *dev, int id, void *data,
> > const struct thermal_zone_device_ops *ops);
> >
> > +void thermal_of_zone_unregister(struct thermal_zone_device *tz);
> > void devm_thermal_of_zone_unregister(struct device *dev, struct thermal_zone_device *tz);
> >
> > #else
> >
> > +static inline
> > +struct thermal_zone_device *thermal_of_zone_register(struct device_node *sensor, int id, void *data,
> > + const struct thermal_zone_device_ops *ops)
> > +{
> > + return ERR_PTR(-ENOTSUPP);
> > +}
> > +
> > static inline
> > struct thermal_zone_device *devm_thermal_of_zone_register(struct device *dev, int id, void *data,
> > const struct thermal_zone_device_ops *ops)
> > @@ -209,6 +219,10 @@ struct thermal_zone_device *devm_thermal_of_zone_register(struct device *dev, in
> > return ERR_PTR(-ENOTSUPP);
> > }
> >
> > +static inline void thermal_of_zone_unregister(struct thermal_zone_device *tz)
> > +{
> > +}
> > +
> > static inline void devm_thermal_of_zone_unregister(struct device *dev,
> > struct thermal_zone_device *tz)
> > {
>
>
> --
> <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs
>
> Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook |
> <http://twitter.com/#!/linaroorg> Twitter |
> <http://www.linaro.org/linaro-blog/> Blog