Re: [PATCH v7 3/7] pmdomain: core: Introduce dev_pm_genpd_rpm_always_on()

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

On Wed, Feb 05, 2025 at 02:15:52PM +0800, Shawn Lin wrote:
> From: Ulf Hansson <ulf.hansson@linaro.org>
> 
> For some usecases a consumer driver requires its device to remain power-on
> from the PM domain perspective during runtime. Using dev PM qos along with
> the genpd governors, doesn't work for this case as would potentially
> prevent the device from being runtime suspended too.
> 
> To support these usecases, let's introduce dev_pm_genpd_rpm_always_on() to
> allow consumers drivers to dynamically control the behaviour in genpd for a
> device that is attached to it.
> 
> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
> Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>

Acked-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

- Mani

> ---
> 
> Changes in v7: None
> Changes in v6:
> - export dev_pm_genpd_rpm_always_on()
> 
> Changes in v5: None
> Changes in v4: None
> Changes in v3: None
> Changes in v2: None
> 
>  drivers/pmdomain/core.c   | 35 +++++++++++++++++++++++++++++++++++
>  include/linux/pm_domain.h |  7 +++++++
>  2 files changed, 42 insertions(+)
> 
> diff --git a/drivers/pmdomain/core.c b/drivers/pmdomain/core.c
> index 6c94137..9b2f28b 100644
> --- a/drivers/pmdomain/core.c
> +++ b/drivers/pmdomain/core.c
> @@ -697,6 +697,37 @@ bool dev_pm_genpd_get_hwmode(struct device *dev)
>  }
>  EXPORT_SYMBOL_GPL(dev_pm_genpd_get_hwmode);
>  
> +/**
> + * dev_pm_genpd_rpm_always_on() - Control if the PM domain can be powered off.
> + *
> + * @dev: Device for which the PM domain may need to stay on for.
> + * @on: Value to set or unset for the condition.
> + *
> + * For some usecases a consumer driver requires its device to remain power-on
> + * from the PM domain perspective during runtime. This function allows the
> + * behaviour to be dynamically controlled for a device attached to a genpd.
> + *
> + * It is assumed that the users guarantee that the genpd wouldn't be detached
> + * while this routine is getting called.
> + *
> + * Return: Returns 0 on success and negative error values on failures.
> + */
> +int dev_pm_genpd_rpm_always_on(struct device *dev, bool on)
> +{
> +	struct generic_pm_domain *genpd;
> +
> +	genpd = dev_to_genpd_safe(dev);
> +	if (!genpd)
> +		return -ENODEV;
> +
> +	genpd_lock(genpd);
> +	dev_gpd_data(dev)->rpm_always_on = on;
> +	genpd_unlock(genpd);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(dev_pm_genpd_rpm_always_on);
> +
>  static int _genpd_power_on(struct generic_pm_domain *genpd, bool timed)
>  {
>  	unsigned int state_idx = genpd->state_idx;
> @@ -868,6 +899,10 @@ static int genpd_power_off(struct generic_pm_domain *genpd, bool one_dev_on,
>  		if (!pm_runtime_suspended(pdd->dev) ||
>  			irq_safe_dev_in_sleep_domain(pdd->dev, genpd))
>  			not_suspended++;
> +
> +		/* The device may need its PM domain to stay powered on. */
> +		if (to_gpd_data(pdd)->rpm_always_on)
> +			return -EBUSY;
>  	}
>  
>  	if (not_suspended > 1 || (not_suspended == 1 && !one_dev_on))
> diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
> index 1aab313..d56a78a 100644
> --- a/include/linux/pm_domain.h
> +++ b/include/linux/pm_domain.h
> @@ -261,6 +261,7 @@ struct generic_pm_domain_data {
>  	unsigned int rpm_pstate;
>  	unsigned int opp_token;
>  	bool hw_mode;
> +	bool rpm_always_on;
>  	void *data;
>  };
>  
> @@ -293,6 +294,7 @@ ktime_t dev_pm_genpd_get_next_hrtimer(struct device *dev);
>  void dev_pm_genpd_synced_poweroff(struct device *dev);
>  int dev_pm_genpd_set_hwmode(struct device *dev, bool enable);
>  bool dev_pm_genpd_get_hwmode(struct device *dev);
> +int dev_pm_genpd_rpm_always_on(struct device *dev, bool on);
>  
>  extern struct dev_power_governor simple_qos_governor;
>  extern struct dev_power_governor pm_domain_always_on_gov;
> @@ -376,6 +378,11 @@ static inline bool dev_pm_genpd_get_hwmode(struct device *dev)
>  	return false;
>  }
>  
> +static inline int dev_pm_genpd_rpm_always_on(struct device *dev, bool on)
> +{
> +	return -EOPNOTSUPP;
> +}
> +
>  #define simple_qos_governor		(*(struct dev_power_governor *)(NULL))
>  #define pm_domain_always_on_gov		(*(struct dev_power_governor *)(NULL))
>  #endif
> -- 
> 2.7.4
> 

-- 
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