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Message-ID: <edbd9d3a-d978-6f64-b1aa-3b1ea226a8bd@codeaurora.org>
Date: Mon, 10 Apr 2017 09:39:15 +0530
From: Rajendra Nayak <rnayak@...eaurora.org>
To: Jon Hunter <jonathanh@...dia.com>,
"Rafael J . Wysocki" <rjw@...ysocki.net>,
Kevin Hilman <khilman@...nel.org>,
Ulf Hansson <ulf.hansson@...aro.org>, geert@...ux-m68k.org
Cc: stanimir.varbanov@...aro.org, sboyd@...eaurora.org,
Marek Szyprowski <m.szyprowski@...sung.com>,
linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-tegra@...r.kernel.org
Subject: Re: [RFC PATCH 2/4] PM / Domains: Add support for explicit control of
PM domains
Hey Jon,
On 03/28/2017 07:44 PM, Jon Hunter wrote:
> The current generic PM domain framework (GenDP) only allows a single
> PM domain to be associated with a given device. There are several
> use-cases for various system-on-chip devices where it is necessary for
> a PM domain consumer to control more than one PM domain where the PM
> domains:
> i). Do not conform to a parent-child relationship so are not nested
> ii). May not be powered on and off at the same time so need independent
> control.
>
> To support the above, add new APIs for GenPD to allow consumers to get,
> power-on, power-off and put PM domains so that they can be explicitly
> controlled by the consumer.
thanks for working on this RFC.
[]..
> +/**
> + * pm_genpd_get - Get a generic I/O PM domain by name
> + * @name: Name of the PM domain.
> + *
> + * Look-ups a PM domain by name. If found, increment the device
> + * count for PM domain to ensure that the PM domain cannot be
> + * removed, increment the suspended count so that it can still
> + * be turned off (when not in-use) and return a pointer to its
> + * generic_pm_domain structure. If not found return ERR_PTR().
> + */
> +struct generic_pm_domain *pm_genpd_get(const char *name)
> +{
> + struct generic_pm_domain *gpd, *genpd = ERR_PTR(-EEXIST);
> +
> + if (!name)
> + return ERR_PTR(-EINVAL);
> +
> + mutex_lock(&gpd_list_lock);
> + list_for_each_entry(gpd, &gpd_list, gpd_list_node) {
> + if (!strcmp(gpd->name, name)) {
> + genpd_lock(gpd);
> + gpd->device_count++;
There apis' should also take a device pointer as a parameter,
so we can track all the devices belonging to a powerdomain.
That would also mean keeping the genpd->dev_list updated instead of
only incrementing the device_count here.
> + gpd->suspended_count++;
> + genpd_unlock(gpd);
> + genpd = gpd;
> + break;
> + }
> + }
> + mutex_unlock(&gpd_list_lock);
> +
> + return genpd;
Instead of returning a pointer to generic_pm_domain to all
consumers (who are then free to poke around it) we should hide
all internal structures handled by the framework and only expose
some kind of a handle to all the consumers.
That would also mean having a clear split of the headers to
distinguish between what's accessible to consumers vs providers.
regards
Rajendra
> +}
> +EXPORT_SYMBOL(pm_genpd_get);
> +
> +/**
> + * pm_genpd_put - Put a generic I/O PM domain
> + * @genpd: Pointer to a PM domain.
> + */
> +void pm_genpd_put(struct generic_pm_domain *genpd)
> +{
> + if (!genpd)
> + return;
> +
> + genpd_lock(genpd);
> +
> + if (WARN_ON(!genpd->device_count || !genpd->suspended_count))
> + goto out;
> +
> + genpd->suspended_count--;
> + genpd->device_count--;
> +
> +out:
> + genpd_unlock(genpd);
> +}
> +EXPORT_SYMBOL(pm_genpd_put);
> +
> +/**
> + * pm_genpd_poweron - Power on a generic I/O PM domain
> + * @genpd: Pointer to a PM domain.
> + *
> + * Powers on a PM domain, if not already on, and decrements the
> + * 'suspended_count' to prevent the PM domain from being powered off.
> + */
> +int pm_genpd_poweron(struct generic_pm_domain *genpd)
> +{
> + if (!genpd)
> + return -EINVAL;
> +
> + genpd_lock(genpd);
> +
> + if (WARN_ON(!genpd->suspended_count))
> + goto out;
> +
> + genpd->suspended_count--;
> + genpd_sync_power_on(genpd, true, 0);
> +
> +out:
> + genpd_unlock(genpd);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(pm_genpd_poweron);
> +
> +/**
> + * pm_genpd_poweroff - Power off a generic I/O PM domain
> + * @genpd: Pointer to a PM domain.
> + *
> + * Increments the 'suspended_count' for a PM domain and if the
> + * 'suspended_count' equals the 'device_count' then will power
> + * off the PM domain.
> + */
> +int pm_genpd_poweroff(struct generic_pm_domain *genpd)
> +{
> + if (!genpd)
> + return -EINVAL;
> +
> + genpd_lock(genpd);
> +
> + if (WARN_ON(genpd->suspended_count >= genpd->device_count))
> + goto out;
> +
> + genpd->suspended_count++;
> + genpd_sync_power_off(genpd, false, 0);
> +
> +out:
> + genpd_unlock(genpd);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(pm_genpd_poweroff);
> +
> #ifdef CONFIG_PM_GENERIC_DOMAINS_OF
>
> typedef struct generic_pm_domain *(*genpd_xlate_t)(struct of_phandle_args *args,
> @@ -2171,7 +2285,6 @@ int of_genpd_parse_idle_states(struct device_node *dn,
> return 0;
> }
> EXPORT_SYMBOL_GPL(of_genpd_parse_idle_states);
> -
> #endif /* CONFIG_PM_GENERIC_DOMAINS_OF */
>
>
> @@ -2223,7 +2336,7 @@ static int pm_genpd_summary_one(struct seq_file *s,
> const char *kobj_path;
> struct gpd_link *link;
> char state[16];
> - int ret;
> + int ret, count;
>
> ret = genpd_lock_interruptible(genpd);
> if (ret)
> @@ -2250,6 +2363,8 @@ static int pm_genpd_summary_one(struct seq_file *s,
> seq_puts(s, ", ");
> }
>
> + count = genpd->device_count;
> +
> list_for_each_entry(pm_data, &genpd->dev_list, list_node) {
> kobj_path = kobject_get_path(&pm_data->dev->kobj,
> genpd_is_irq_safe(genpd) ?
> @@ -2260,8 +2375,12 @@ static int pm_genpd_summary_one(struct seq_file *s,
> seq_printf(s, "\n %-50s ", kobj_path);
> rtpm_status_str(s, pm_data->dev);
> kfree(kobj_path);
> + count--;
> }
>
> + if (count > 0)
> + seq_printf(s, "\n unknown (%d)", count);
> +
> seq_puts(s, "\n");
> exit:
> genpd_unlock(genpd);
> diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
> index 5339ed5bd6f9..b3aa1f237d96 100644
> --- a/include/linux/pm_domain.h
> +++ b/include/linux/pm_domain.h
> @@ -143,6 +143,10 @@ extern int pm_genpd_remove_subdomain(struct generic_pm_domain *genpd,
> extern int pm_genpd_init(struct generic_pm_domain *genpd,
> struct dev_power_governor *gov, bool is_off);
> extern int pm_genpd_remove(struct generic_pm_domain *genpd);
> +extern struct generic_pm_domain *pm_genpd_get(const char *name);
> +extern void pm_genpd_put(struct generic_pm_domain *genpd);
> +extern int pm_genpd_poweron(struct generic_pm_domain *genpd);
> +extern int pm_genpd_poweroff(struct generic_pm_domain *genpd);
>
> extern struct dev_power_governor simple_qos_governor;
> extern struct dev_power_governor pm_domain_always_on_gov;
> @@ -182,6 +186,20 @@ static inline int pm_genpd_remove(struct generic_pm_domain *genpd)
> {
> return -ENOTSUPP;
> }
> +static inline struct generic_pm_domain *pm_genpd_get(const char *name)
> +{
> + return ERR_PTR(-ENOTSUPP);
> +}
> +
> +static inline void pm_genpd_put(struct generic_pm_domain *genpd) {}
> +static inline int pm_genpd_poweron(struct generic_pm_domain *genpd)
> +{
> + return -ENOTSUPP;
> +}
> +static inline int pm_genpd_poweroff(struct generic_pm_domain *genpd)
> +{
> + return -ENOTSUPP;
> +}
>
> #define simple_qos_governor (*(struct dev_power_governor *)(NULL))
> #define pm_domain_always_on_gov (*(struct dev_power_governor *)(NULL))
>
--
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