linux-kernel - Re: [Patch v5 1/6] PM/Domains: Add support for retrieving genpd performance states information

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Date:   Fri, 27 Mar 2020 15:33:22 -0700
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Thara Gopinath <thara.gopinath@...aro.org>
Cc:     rui.zhang@...el.com, ulf.hansson@...aro.org,
        daniel.lezcano@...aro.org, agross@...nel.org, robh@...nel.org,
        amit.kucheria@...durent.com, mark.rutland@....com,
        rjw@...ysocki.net, linux-pm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [Patch v5 1/6] PM/Domains: Add support for retrieving genpd
 performance states information

On Thu 19 Mar 18:41 PDT 2020, Thara Gopinath wrote:

> Add two new APIs in the genpd framework, dev_pm_genpd_get_performance_state
> to return the current performance state of a power domain and
> dev_pm_genpd_performance_state_count to return the total number of
> performance states supported by a power domain. Since the genpd framework
> does not maintain a count of number of performance states supported by a
> power domain, introduce a new callback(.get_performance_state_count) that
> can be used to retrieve this information from power domain drivers.
> 
> These APIs are added to aid the implementation of a power domain as a
> warming device. Linux kernel cooling device framework(into which warming
> device can be plugged in) requires during initialization to be provided
> with the maximum number of states that can be supported. When a power
> domain acts as a warming device, the max state is the max number of
> perfomrance states supported by the power domain. The cooling device
> framework implements API to retrieve the current state of the cooling
> device. This in turn translates to the current performance state of the
> power domain.
> 
> Reviewed-by: Ulf Hansson <ulf.hansson@...aro.org>
> Signed-off-by: Thara Gopinath <thara.gopinath@...aro.org>

Reviewed-by: Bjorn Andersson <bjorn.andersson@...aro.org>

> ---
>  drivers/base/power/domain.c | 37 +++++++++++++++++++++++++++++++++++++
>  include/linux/pm_domain.h   | 13 +++++++++++++
>  2 files changed, 50 insertions(+)
> 
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index 959d6d5eb000..d0297c48fa79 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -408,6 +408,43 @@ int dev_pm_genpd_set_performance_state(struct device *dev, unsigned int state)
>  }
>  EXPORT_SYMBOL_GPL(dev_pm_genpd_set_performance_state);
>  
> +int dev_pm_genpd_get_performance_state(struct device *dev)
> +{
> +	struct generic_pm_domain *genpd;
> +	unsigned int state;
> +
> +	genpd = dev_to_genpd_safe(dev);
> +	if (IS_ERR(genpd))
> +		return -ENODEV;
> +
> +	genpd_lock(genpd);
> +	state = genpd->performance_state;
> +	genpd_unlock(genpd);
> +
> +	return state;
> +}
> +EXPORT_SYMBOL_GPL(dev_pm_genpd_get_performance_state);
> +
> +int dev_pm_genpd_performance_state_count(struct device *dev)
> +{
> +	struct generic_pm_domain *genpd;
> +	int count;
> +
> +	genpd = dev_to_genpd_safe(dev);
> +	if (IS_ERR(genpd))
> +		return -ENODEV;
> +
> +	if (unlikely(!genpd->get_performance_state_count))
> +		return -EINVAL;
> +
> +	genpd_lock(genpd);
> +	count = genpd->get_performance_state_count(genpd);
> +	genpd_unlock(genpd);
> +
> +	return count;
> +}
> +EXPORT_SYMBOL_GPL(dev_pm_genpd_performance_state_count);
> +
>  static int _genpd_power_on(struct generic_pm_domain *genpd, bool timed)
>  {
>  	unsigned int state_idx = genpd->state_idx;
> diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
> index 9ec78ee53652..7d415350380f 100644
> --- a/include/linux/pm_domain.h
> +++ b/include/linux/pm_domain.h
> @@ -117,6 +117,7 @@ struct generic_pm_domain {
>  						 struct dev_pm_opp *opp);
>  	int (*set_performance_state)(struct generic_pm_domain *genpd,
>  				     unsigned int state);
> +	int (*get_performance_state_count)(struct generic_pm_domain *genpd);
>  	struct gpd_dev_ops dev_ops;
>  	s64 max_off_time_ns;	/* Maximum allowed "suspended" time. */
>  	bool max_off_time_changed;
> @@ -204,6 +205,8 @@ int pm_genpd_init(struct generic_pm_domain *genpd,
>  		  struct dev_power_governor *gov, bool is_off);
>  int pm_genpd_remove(struct generic_pm_domain *genpd);
>  int dev_pm_genpd_set_performance_state(struct device *dev, unsigned int state);
> +int dev_pm_genpd_get_performance_state(struct device *dev);
> +int dev_pm_genpd_performance_state_count(struct device *dev);
>  
>  extern struct dev_power_governor simple_qos_governor;
>  extern struct dev_power_governor pm_domain_always_on_gov;
> @@ -251,6 +254,16 @@ static inline int dev_pm_genpd_set_performance_state(struct device *dev,
>  	return -ENOTSUPP;
>  }
>  
> +static inline int dev_pm_genpd_get_performance_state(struct device *dev)
> +{
> +	return -ENOTSUPP;
> +}
> +
> +static inline int dev_pm_genpd_performance_state_count(struct device *dev)
> +{
> +	return -ENOTSUPP;
> +}
> +
>  #define simple_qos_governor		(*(struct dev_power_governor *)(NULL))
>  #define pm_domain_always_on_gov		(*(struct dev_power_governor *)(NULL))
>  #endif
> -- 
> 2.20.1
>