[V6,3/7] cpufreq: call driver's suspend/resume for each policy

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.

Tested-by: Lan Tianyu <tianyu.lan@intel.com>
Tested-by: Nishanth Menon <nm@ti.com>
Tested-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 drivers/cpufreq/cpufreq.c | 98 +++++++++--------------------------------------
 1 file changed, 18 insertions(+), 80 deletions(-)

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@intel.com>
> Tested-by: Nishanth Menon <nm@ti.com>
> Tested-by: Stephen Warren <swarren@nvidia.com>
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.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;
>  }
>