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

[Daniel Lezcano <daniel.lezcano@linaro.org>]

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


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>
> ---
>   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)
>   {


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