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Date: Sun, 02 Mar 2014 01:02:48 +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 3/7] cpufreq: call driver's suspend/resume for each policy
On Monday, February 17, 2014 02:55:09 PM Viresh Kumar wrote:
> Earlier cpufreq suspend/resume callbacks into drivers were getting called only
> for the boot CPU, as by the time callbacks were called non-boot CPUs were
> already removed. Because we might still need driver specific actions on
> suspend/resume, its better to use earlier infrastructure from the early
> suspend/late resume calls.
>
> In effect, we call suspend/resume for each policy. The resume part also takes
> care of synchronising frequency for boot CPU, which might turn out be different
> than what cpufreq core believes.
>
> Hence, the earlier syscore infrastructure is getting removed now.
This should be folded into [1-2/7] too, I think, because otherwise you have a
gap where things are kind of in between the two solutions.
> Tested-by: Lan Tianyu <tianyu.lan@...el.com>
> Tested-by: Nishanth Menon <nm@...com>
> Tested-by: Stephen Warren <swarren@...dia.com>
> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
> ---
> drivers/cpufreq/cpufreq.c | 98 +++++++++--------------------------------------
> 1 file changed, 18 insertions(+), 80 deletions(-)
>
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 4ca2297..c240232 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -27,7 +27,6 @@
> #include <linux/mutex.h>
> #include <linux/slab.h>
> #include <linux/suspend.h>
> -#include <linux/syscore_ops.h>
> #include <linux/tick.h>
> #include <trace/events/power.h>
>
> @@ -1599,10 +1598,15 @@ void cpufreq_suspend(void)
>
> pr_debug("%s: Suspending Governors\n", __func__);
>
> - list_for_each_entry(policy, &cpufreq_policy_list, policy_list)
> + 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_suspended = true;
> }
> @@ -1627,91 +1631,26 @@ void cpufreq_resume(void)
>
> cpufreq_suspended = false;
>
> - list_for_each_entry(policy, &cpufreq_policy_list, policy_list)
> + 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);
> -}
> -
> -/**
> - * cpufreq_bp_suspend - Prepare the boot CPU for system suspend.
> - *
> - * This function is only executed for the boot processor. The other CPUs
> - * have been put offline by means of CPU hotplug.
> - */
> -static int cpufreq_bp_suspend(void)
> -{
> - int ret = 0;
> -
> - int cpu = smp_processor_id();
> - struct cpufreq_policy *policy;
> -
> - pr_debug("suspending cpu %u\n", cpu);
> -
> - /* If there's no policy for the boot CPU, we have nothing to do. */
> - policy = cpufreq_cpu_get(cpu);
> - if (!policy)
> - return 0;
> -
> - 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);
> - }
> -
> - cpufreq_cpu_put(policy);
> - return ret;
> -}
> + else if (cpufreq_driver->resume
> + && cpufreq_driver->resume(policy))
> + pr_err("%s: Failed to resume driver: %p\n", __func__,
> + policy);
>
> -/**
> - * cpufreq_bp_resume - Restore proper frequency handling of the boot CPU.
> - *
> - * 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.
> - */
> -static void cpufreq_bp_resume(void)
> -{
> - int ret = 0;
> -
> - int cpu = smp_processor_id();
> - struct cpufreq_policy *policy;
> -
> - pr_debug("resuming cpu %u\n", cpu);
> -
> - /* If there's no policy for the boot CPU, we have nothing to do. */
> - policy = cpufreq_cpu_get(cpu);
> - if (!policy)
> - 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;
> - }
> + /*
> + * 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);
> }
> -
> - schedule_work(&policy->update);
> -
> -fail:
> - cpufreq_cpu_put(policy);
> }
>
> -static struct syscore_ops cpufreq_syscore_ops = {
> - .suspend = cpufreq_bp_suspend,
> - .resume = cpufreq_bp_resume,
> -};
> -
> /**
> * cpufreq_get_current_driver - return current driver's name
> *
> @@ -2477,7 +2416,6 @@ 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;
> }
>
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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