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Date: Wed, 19 Dec 2018 10:53:45 +0100
From: Daniel Lezcano <daniel.lezcano@...aro.org>
To: Ulf Hansson <ulf.hansson@...aro.org>,
"Rafael J . Wysocki" <rjw@...ysocki.net>,
Sudeep Holla <sudeep.holla@....com>,
Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
Mark Rutland <mark.rutland@....com>, linux-pm@...r.kernel.org
Cc: "Raju P . L . S . S . S . N" <rplsssn@...eaurora.org>,
Stephen Boyd <sboyd@...nel.org>,
Tony Lindgren <tony@...mide.com>,
Kevin Hilman <khilman@...nel.org>,
Lina Iyer <ilina@...eaurora.org>,
Viresh Kumar <viresh.kumar@...aro.org>,
Vincent Guittot <vincent.guittot@...aro.org>,
Geert Uytterhoeven <geert+renesas@...der.be>,
linux-arm-kernel@...ts.infradead.org,
linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v10 02/27] PM / Domains: Add support for CPU devices to
genpd
On 29/11/2018 18:46, Ulf Hansson wrote:
> To enable a device belonging to a CPU to be attached to a PM domain managed
> by genpd, let's do a few changes to it, as to make it convenient to manage
> the specifics around CPUs.
>
> To be able to quickly find out what CPUs that are attached to a genpd,
> which typically becomes useful from a genpd governor as following changes
> is about to show, let's add a cpumask to the struct generic_pm_domain. At
> the point when a CPU device gets attached to a genpd, let's update its
> cpumask. Moreover, let's also propagate changes to the cpumask upwards in
> the topology to the master PM domains. In this way, the cpumask for a genpd
> hierarchically reflects all CPUs attached to the topology below it.
>
> Finally, let's make this an opt-in feature, to avoid having to manage CPUs
> and the cpumask for a genpd that doesn't need it. For that reason, let's
> add a new genpd configuration bit, GENPD_FLAG_CPU_DOMAIN.
>
> Cc: Lina Iyer <ilina@...eaurora.org>
> Co-developed-by: Lina Iyer <lina.iyer@...aro.org>
> Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
> ---
>
> Changes in v10:
> - Don't allocate the cpumask when not used.
> - Simplify the code that updates the cpumask.
> - Document the GENPD_FLAG_CPU_DOMAIN.
>
> ---
> drivers/base/power/domain.c | 66 ++++++++++++++++++++++++++++++++++++-
> include/linux/pm_domain.h | 13 ++++++++
> 2 files changed, 78 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index e27b91d36a2a..c3ff8e395308 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -20,6 +20,7 @@
> #include <linux/sched.h>
> #include <linux/suspend.h>
> #include <linux/export.h>
> +#include <linux/cpu.h>
>
> #include "power.h"
>
> @@ -126,6 +127,7 @@ static const struct genpd_lock_ops genpd_spin_ops = {
> #define genpd_is_irq_safe(genpd) (genpd->flags & GENPD_FLAG_IRQ_SAFE)
> #define genpd_is_always_on(genpd) (genpd->flags & GENPD_FLAG_ALWAYS_ON)
> #define genpd_is_active_wakeup(genpd) (genpd->flags & GENPD_FLAG_ACTIVE_WAKEUP)
> +#define genpd_is_cpu_domain(genpd) (genpd->flags & GENPD_FLAG_CPU_DOMAIN)
>
> static inline bool irq_safe_dev_in_no_sleep_domain(struct device *dev,
> const struct generic_pm_domain *genpd)
> @@ -1377,6 +1379,56 @@ static void genpd_free_dev_data(struct device *dev,
> dev_pm_put_subsys_data(dev);
> }
>
> +static void __genpd_update_cpumask(struct generic_pm_domain *genpd,
> + int cpu, bool set, unsigned int depth)
> +{
> + struct gpd_link *link;
> +
> + if (!genpd_is_cpu_domain(genpd))
> + return;
With this test, we won't continue updating the cpumask for the other
masters. Is it done on purpose ?
> + list_for_each_entry(link, &genpd->slave_links, slave_node) {
> + struct generic_pm_domain *master = link->master;
> +
> + genpd_lock_nested(master, depth + 1);
> + __genpd_update_cpumask(master, cpu, set, depth + 1);
> + genpd_unlock(master);
> + }
> +
> + if (set)
> + cpumask_set_cpu(cpu, genpd->cpus);
> + else
> + cpumask_clear_cpu(cpu, genpd->cpus);
> +}
> +
> +static void genpd_update_cpumask(struct generic_pm_domain *genpd,
> + struct device *dev, bool set)
> +{
> + int cpu;
> +
> + if (!genpd_is_cpu_domain(genpd))
> + return;
> +
> + for_each_possible_cpu(cpu) {
> + if (get_cpu_device(cpu) == dev) {
> + __genpd_update_cpumask(genpd, cpu, set, 0);
> + return;
> + }
> + }
> +}
> +
> +static void genpd_set_cpumask(struct generic_pm_domain *genpd,
> + struct device *dev)
> +{
> + genpd_update_cpumask(genpd, dev, true);
> +}
> +
> +static void genpd_clear_cpumask(struct generic_pm_domain *genpd,
> + struct device *dev)
> +{
> + genpd_update_cpumask(genpd, dev, false);
> +}
> +
> static int genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,
> struct gpd_timing_data *td)
> {
> @@ -1398,6 +1450,8 @@ static int genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,
> if (ret)
> goto out;
>
> + genpd_set_cpumask(genpd, dev);
> +
> dev_pm_domain_set(dev, &genpd->domain);
>
> genpd->device_count++;
> @@ -1459,6 +1513,7 @@ static int genpd_remove_device(struct generic_pm_domain *genpd,
> if (genpd->detach_dev)
> genpd->detach_dev(genpd, dev);
>
> + genpd_clear_cpumask(genpd, dev);
> dev_pm_domain_set(dev, NULL);
>
> list_del_init(&pdd->list_node);
> @@ -1686,11 +1741,18 @@ int pm_genpd_init(struct generic_pm_domain *genpd,
> if (genpd_is_always_on(genpd) && !genpd_status_on(genpd))
> return -EINVAL;
>
> + if (genpd_is_cpu_domain(genpd) &&
> + !zalloc_cpumask_var(&genpd->cpus, GFP_KERNEL))
> + return -ENOMEM;
> +
> /* Use only one "off" state if there were no states declared */
> if (genpd->state_count == 0) {
> ret = genpd_set_default_power_state(genpd);
> - if (ret)
> + if (ret) {
> + if (genpd_is_cpu_domain(genpd))
> + free_cpumask_var(genpd->cpus);
> return ret;
> + }
> } else if (!gov) {
> pr_warn("%s : no governor for states\n", genpd->name);
> }
> @@ -1736,6 +1798,8 @@ static int genpd_remove(struct generic_pm_domain *genpd)
> list_del(&genpd->gpd_list_node);
> genpd_unlock(genpd);
> cancel_work_sync(&genpd->power_off_work);
> + if (genpd_is_cpu_domain(genpd))
> + free_cpumask_var(genpd->cpus);
> if (genpd->free_state) {
> kfree(genpd->states);
> genpd->states = NULL;
> diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
> index f9e09bd4152c..5a4673605d22 100644
> --- a/include/linux/pm_domain.h
> +++ b/include/linux/pm_domain.h
> @@ -16,6 +16,7 @@
> #include <linux/of.h>
> #include <linux/notifier.h>
> #include <linux/spinlock.h>
> +#include <linux/cpumask.h>
>
> /*
> * Flags to control the behaviour of a genpd.
> @@ -42,11 +43,22 @@
> * GENPD_FLAG_ACTIVE_WAKEUP: Instructs genpd to keep the PM domain powered
> * on, in case any of its attached devices is used
> * in the wakeup path to serve system wakeups.
> + *
> + * GENPD_FLAG_CPU_DOMAIN: Instructs genpd that it should expect to get
> + * devices attached, which may belong to CPUs or
> + * possibly have subdomains with CPUs attached.
> + * This flag enables the genpd backend driver to
> + * deploy idle power management support for CPUs
> + * and groups of CPUs. Note that, the backend
> + * driver must then comply with the so called,
> + * last-man-standing algorithm, for the CPUs in the
> + * PM domain.
> */
> #define GENPD_FLAG_PM_CLK (1U << 0)
> #define GENPD_FLAG_IRQ_SAFE (1U << 1)
> #define GENPD_FLAG_ALWAYS_ON (1U << 2)
> #define GENPD_FLAG_ACTIVE_WAKEUP (1U << 3)
> +#define GENPD_FLAG_CPU_DOMAIN (1U << 4)
>
> enum gpd_status {
> GPD_STATE_ACTIVE = 0, /* PM domain is active */
> @@ -93,6 +105,7 @@ struct generic_pm_domain {
> unsigned int suspended_count; /* System suspend device counter */
> unsigned int prepared_count; /* Suspend counter of prepared devices */
> unsigned int performance_state; /* Aggregated max performance state */
> + cpumask_var_t cpus; /* A cpumask of the attached CPUs */
> int (*power_off)(struct generic_pm_domain *domain);
> int (*power_on)(struct generic_pm_domain *domain);
> unsigned int (*opp_to_performance_state)(struct generic_pm_domain *genpd,
>
--
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