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Message-ID: <6523021.Z15JvIV2Lx@vostro.rjw.lan>
Date: Fri, 07 Mar 2014 02:01:14 +0100
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Viresh Kumar <viresh.kumar@...aro.org>
Cc: linaro-kernel@...ts.linaro.org, cpufreq@...r.kernel.org,
linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org, nm@...com,
swarren@...dotorg.org, kgene.kim@...sung.com, jinchoi@...adcom.com,
tianyu.lan@...el.com, sebastian.capella@...aro.org,
jhbird.choi@...sung.com
Subject: Re: [PATCH V6 Resend 1/5] cpufreq: suspend governors on system suspend/hibernate
On Tuesday, March 04, 2014 11:00:26 AM Viresh Kumar wrote:
> This patch adds cpufreq suspend/resume calls to dpm_{suspend|resume}() for
> handling suspend/resume of cpufreq governors.
>
> Lan Tianyu (Intel) & Jinhyuk Choi (Broadcom) found an issue where tunables
> configuration for clusters/sockets with non-boot CPUs was getting lost after
> suspend/resume, as we were notifying governors with CPUFREQ_GOV_POLICY_EXIT on
> removal of the last cpu for that policy and so deallocating memory for tunables.
> This is fixed by this patch as we don't allow any operation on governors after
> device suspend and before device resume now.
>
> We could have added these callbacks at dpm_{suspend|resume}_noirq() level but
> the problem here is that most of the devices (i.e. devices with ->suspend()
> callbacks) have already been suspended by now and so if drivers want to change
> frequency before suspending, then it might not be possible for many platforms
> (which depend on other peripherals like i2c, regulators, etc).
>
> Reported-and-tested-by: Lan Tianyu <tianyu.lan@...el.com>
> Reported-by: Jinhyuk Choi <jinchoi@...adcom.com>
> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
Queued up for 3.15, thanks!
> ---
> V5->V6: 1-2-3/7 merged into 1/5
>
> drivers/base/power/main.c | 5 +++
> drivers/cpufreq/cpufreq.c | 111 +++++++++++++++++++++++-----------------------
> include/linux/cpufreq.h | 8 ++++
> 3 files changed, 69 insertions(+), 55 deletions(-)
>
> diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
> index 42355e4..86d5e4f 100644
> --- a/drivers/base/power/main.c
> +++ b/drivers/base/power/main.c
> @@ -29,6 +29,7 @@
> #include <linux/async.h>
> #include <linux/suspend.h>
> #include <trace/events/power.h>
> +#include <linux/cpufreq.h>
> #include <linux/cpuidle.h>
> #include <linux/timer.h>
>
> @@ -866,6 +867,8 @@ void dpm_resume(pm_message_t state)
> mutex_unlock(&dpm_list_mtx);
> async_synchronize_full();
> dpm_show_time(starttime, state, NULL);
> +
> + cpufreq_resume();
> }
>
> /**
> @@ -1434,6 +1437,8 @@ int dpm_suspend(pm_message_t state)
>
> might_sleep();
>
> + cpufreq_suspend();
> +
> mutex_lock(&dpm_list_mtx);
> pm_transition = state;
> async_error = 0;
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 56b7b1b..2e43c08 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -26,7 +26,7 @@
> #include <linux/module.h>
> #include <linux/mutex.h>
> #include <linux/slab.h>
> -#include <linux/syscore_ops.h>
> +#include <linux/suspend.h>
> #include <linux/tick.h>
> #include <trace/events/power.h>
>
> @@ -47,6 +47,9 @@ static LIST_HEAD(cpufreq_policy_list);
> static DEFINE_PER_CPU(char[CPUFREQ_NAME_LEN], cpufreq_cpu_governor);
> #endif
>
> +/* Flag to suspend/resume CPUFreq governors */
> +static bool cpufreq_suspended;
> +
> static inline bool has_target(void)
> {
> return cpufreq_driver->target_index || cpufreq_driver->target;
> @@ -1576,82 +1579,77 @@ static struct subsys_interface cpufreq_interface = {
> };
>
> /**
> - * cpufreq_bp_suspend - Prepare the boot CPU for system suspend.
> + * cpufreq_suspend() - Suspend CPUFreq governors
> *
> - * This function is only executed for the boot processor. The other CPUs
> - * have been put offline by means of CPU hotplug.
> + * Called during system wide Suspend/Hibernate cycles for suspending governors
> + * as some platforms can't change frequency after this point in suspend cycle.
> + * Because some of the devices (like: i2c, regulators, etc) they use for
> + * changing frequency are suspended quickly after this point.
> */
> -static int cpufreq_bp_suspend(void)
> +void cpufreq_suspend(void)
> {
> - int ret = 0;
> -
> - int cpu = smp_processor_id();
> struct cpufreq_policy *policy;
>
> - pr_debug("suspending cpu %u\n", cpu);
> + if (!cpufreq_driver)
> + return;
>
> - /* If there's no policy for the boot CPU, we have nothing to do. */
> - policy = cpufreq_cpu_get(cpu);
> - if (!policy)
> - return 0;
> + if (!has_target())
> + return;
>
> - if (cpufreq_driver->suspend) {
> - ret = cpufreq_driver->suspend(policy);
> - if (ret)
> - printk(KERN_ERR "cpufreq: suspend failed in ->suspend "
> - "step on CPU %u\n", policy->cpu);
> + pr_debug("%s: Suspending Governors\n", __func__);
> +
> + list_for_each_entry(policy, &cpufreq_policy_list, policy_list) {
> + if (__cpufreq_governor(policy, CPUFREQ_GOV_STOP))
> + pr_err("%s: Failed to stop governor for policy: %p\n",
> + __func__, policy);
> + else if (cpufreq_driver->suspend
> + && cpufreq_driver->suspend(policy))
> + pr_err("%s: Failed to suspend driver: %p\n", __func__,
> + policy);
> }
>
> - cpufreq_cpu_put(policy);
> - return ret;
> + cpufreq_suspended = true;
> }
>
> /**
> - * cpufreq_bp_resume - Restore proper frequency handling of the boot CPU.
> + * cpufreq_resume() - Resume CPUFreq governors
> *
> - * 1.) resume CPUfreq hardware support (cpufreq_driver->resume())
> - * 2.) schedule call cpufreq_update_policy() ASAP as interrupts are
> - * restored. It will verify that the current freq is in sync with
> - * what we believe it to be. This is a bit later than when it
> - * should be, but nonethteless it's better than calling
> - * cpufreq_driver->get() here which might re-enable interrupts...
> - *
> - * This function is only executed for the boot CPU. The other CPUs have not
> - * been turned on yet.
> + * Called during system wide Suspend/Hibernate cycle for resuming governors that
> + * are suspended with cpufreq_suspend().
> */
> -static void cpufreq_bp_resume(void)
> +void cpufreq_resume(void)
> {
> - int ret = 0;
> -
> - int cpu = smp_processor_id();
> struct cpufreq_policy *policy;
>
> - pr_debug("resuming cpu %u\n", cpu);
> + if (!cpufreq_driver)
> + return;
>
> - /* If there's no policy for the boot CPU, we have nothing to do. */
> - policy = cpufreq_cpu_get(cpu);
> - if (!policy)
> + if (!has_target())
> return;
>
> - if (cpufreq_driver->resume) {
> - ret = cpufreq_driver->resume(policy);
> - if (ret) {
> - printk(KERN_ERR "cpufreq: resume failed in ->resume "
> - "step on CPU %u\n", policy->cpu);
> - goto fail;
> - }
> - }
> + pr_debug("%s: Resuming Governors\n", __func__);
>
> - schedule_work(&policy->update);
> + cpufreq_suspended = false;
>
> -fail:
> - cpufreq_cpu_put(policy);
> -}
> + list_for_each_entry(policy, &cpufreq_policy_list, policy_list) {
> + if (__cpufreq_governor(policy, CPUFREQ_GOV_START)
> + || __cpufreq_governor(policy, CPUFREQ_GOV_LIMITS))
> + pr_err("%s: Failed to start governor for policy: %p\n",
> + __func__, policy);
> + else if (cpufreq_driver->resume
> + && cpufreq_driver->resume(policy))
> + pr_err("%s: Failed to resume driver: %p\n", __func__,
> + policy);
>
> -static struct syscore_ops cpufreq_syscore_ops = {
> - .suspend = cpufreq_bp_suspend,
> - .resume = cpufreq_bp_resume,
> -};
> + /*
> + * schedule call cpufreq_update_policy() for boot CPU, i.e. last
> + * policy in list. It will verify that the current freq is in
> + * sync with what we believe it to be.
> + */
> + if (list_is_last(&policy->policy_list, &cpufreq_policy_list))
> + schedule_work(&policy->update);
> + }
> +}
>
> /**
> * cpufreq_get_current_driver - return current driver's name
> @@ -1868,6 +1866,10 @@ static int __cpufreq_governor(struct cpufreq_policy *policy,
> struct cpufreq_governor *gov = NULL;
> #endif
>
> + /* Don't start any governor operations if we are entering suspend */
> + if (cpufreq_suspended)
> + return 0;
> +
> if (policy->governor->max_transition_latency &&
> policy->cpuinfo.transition_latency >
> policy->governor->max_transition_latency) {
> @@ -2407,7 +2409,6 @@ static int __init cpufreq_core_init(void)
>
> cpufreq_global_kobject = kobject_create();
> BUG_ON(!cpufreq_global_kobject);
> - register_syscore_ops(&cpufreq_syscore_ops);
>
> return 0;
> }
> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
> index 4d89e0e..94ed907 100644
> --- a/include/linux/cpufreq.h
> +++ b/include/linux/cpufreq.h
> @@ -296,6 +296,14 @@ cpufreq_verify_within_cpu_limits(struct cpufreq_policy *policy)
> policy->cpuinfo.max_freq);
> }
>
> +#ifdef CONFIG_CPU_FREQ
> +void cpufreq_suspend(void);
> +void cpufreq_resume(void);
> +#else
> +static inline void cpufreq_suspend(void) {}
> +static inline void cpufreq_resume(void) {}
> +#endif
> +
> /*********************************************************************
> * CPUFREQ NOTIFIER INTERFACE *
> *********************************************************************/
>
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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