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Date: Thu, 4 Apr 2013 16:11:48 +0530
From: Rajagopal Venkat <rajagopal.venkat@...aro.org>
To: Kevin Hilman <khilman@...aro.org>
Cc: myungjoo.ham@...sung.com, rjw@...k.pl,
Alan Stern <stern@...land.harvard.edu>, patches@...aro.org,
linaro-kernel@...ts.linaro.org, linux-pm@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] PM / devfreq: tie suspend/resume to runtime-pm
On 3 April 2013 23:46, Kevin Hilman <khilman@...aro.org> wrote:
> Rajagopal Venkat <rajagopal.venkat@...aro.org> writes:
>
>> Devfreq core suspend/resume of a device is explicitly handled
>> by devfreq driver through devfreq_suspend_device() and
>> devfreq_resume_device() apis typically called from runtime
>> suspend/resume callbacks. This patch aims to take away this
>> from devfreq drivers and handle it from runtime-pm core. So
>> that device devfreq core suspend/resume is automatically done
>> with runtime pm suspend/resume. The devfreq drivers shouldn't
>> be concerned on when to suspend/resume the devfreq.
>
> The terminology is a bit confusing here since you're mixing runtime
> suspend/resume and just suspend/resume. AFAICT, this patch is only
> handling devfreq in the runtime PM core, correct?
Yes correct. The suspend/resume refers to devfreq core suspend/resume
of a device. Nothing to do with system wide suspend/resume. May be I
am not clear enough. I will update it.
>
> Also, how does this work when multiple devices may be using the same
> devfreq instance? Using this patch, it looks like the devfreq governor
> will be shutdown as soon as the first device runtime suspends, right?
As per the devfre
>
>> This patch is targeted to handle devfreq core load monitoring
>> suspend/resume only. Not the actual hardware itself. All the
>> resources like clocks and regulators must still be handled by
>> devfreq driver using runtime-pm. The sequence of devfreq and
> ^^^^^^^
> devfreq driver? Did you mean device driver?
Yes device driver.
>
> Kevin
>
>> device runtime suspend/resume is,
>>
>> pm_runtime_suspend(dev) will first suspend device devfreq
>> (if available) before device is suspended to ensure devfreq load
>> monitoring is stopped and no device resources like clocks are
>> accessed while device suspend is in progress.
>>
>> pm_runtime_resume(dev) will resume device devfreq(if available)
>> after device is resumed to ensure device resources like clocks
>> are ready for use.
>>
>> As devfreq suspend/resume is done automatically from runtime-pm,
>> this patch removes the existing devfreq_suspend_device() and
>> devfreq_resume_device() apis.
>>
>> Signed-off-by: Rajagopal Venkat <rajagopal.venkat@...aro.org>
>> ---
>> drivers/base/power/runtime.c | 21 ++++++++++++-
>> drivers/devfreq/devfreq.c | 69 +++++++++++++++++++++++++++++++++++++++---
>> include/linux/devfreq.h | 18 +++--------
>> include/linux/pm.h | 2 ++
>> 4 files changed, 91 insertions(+), 19 deletions(-)
>>
>> diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
>> index 3148b10..2438abc 100644
>> --- a/drivers/base/power/runtime.c
>> +++ b/drivers/base/power/runtime.c
>> @@ -11,6 +11,7 @@
>> #include <linux/export.h>
>> #include <linux/pm_runtime.h>
>> #include <trace/events/rpm.h>
>> +#include <linux/devfreq.h>
>> #include "power.h"
>>
>> static int rpm_resume(struct device *dev, int rpmflags);
>> @@ -406,6 +407,14 @@ static int rpm_suspend(struct device *dev, int rpmflags)
>>
>> __update_runtime_status(dev, RPM_SUSPENDING);
>>
>> + /*
>> + * Try suspending devfreq before device is runtime suspended.
>> + * It wouldn't make sense to continue devfreq load monitoring
>> + * when device is runtime suspended.
>> + */
>> + if (dev->power.devfreq && dev->power.devfreq->runtime_suspend)
>> + dev->power.devfreq->runtime_suspend(dev);
>> +
>> if (dev->pm_domain)
>> callback = dev->pm_domain->ops.runtime_suspend;
>> else if (dev->type && dev->type->pm)
>> @@ -421,8 +430,12 @@ static int rpm_suspend(struct device *dev, int rpmflags)
>> callback = dev->driver->pm->runtime_suspend;
>>
>> retval = rpm_callback(callback, dev);
>> - if (retval)
>> + if (retval) {
>> + /* Resume back devfreq on device suspend failure */
>> + if (dev->power.devfreq && dev->power.devfreq->runtime_resume)
>> + dev->power.devfreq->runtime_resume(dev);
>> goto fail;
>> + }
>>
>> no_callback:
>> __update_runtime_status(dev, RPM_SUSPENDED);
>> @@ -661,6 +674,12 @@ static int rpm_resume(struct device *dev, int rpmflags)
>> __update_runtime_status(dev, RPM_ACTIVE);
>> if (parent)
>> atomic_inc(&parent->power.child_count);
>> + /*
>> + * Resume devfreq after runtime resume sequence to ensure
>> + * device resources are available for devfreq load monitoring.
>> + */
>> + if (dev->power.devfreq && dev->power.devfreq->runtime_resume)
>> + dev->power.devfreq->runtime_resume(dev);
>> }
>> wake_up_all(&dev->power.wait_queue);
>>
>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>> index 44c4079..b8dab0d 100644
>> --- a/drivers/devfreq/devfreq.c
>> +++ b/drivers/devfreq/devfreq.c
>> @@ -25,6 +25,7 @@
>> #include <linux/list.h>
>> #include <linux/printk.h>
>> #include <linux/hrtimer.h>
>> +#include <linux/pm_runtime.h>
>> #include "governor.h"
>>
>> static struct class *devfreq_class;
>> @@ -42,6 +43,9 @@ static LIST_HEAD(devfreq_governor_list);
>> static LIST_HEAD(devfreq_list);
>> static DEFINE_MUTEX(devfreq_list_lock);
>>
>> +static void devfreq_runtime_suspend(struct device *dev);
>> +static void devfreq_runtime_resume(struct device *dev);
>> +
>> /**
>> * find_device_devfreq() - find devfreq struct using device pointer
>> * @dev: device pointer used to lookup device devfreq.
>> @@ -387,6 +391,8 @@ static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type,
>> */
>> static void _remove_devfreq(struct devfreq *devfreq, bool skip)
>> {
>> + unsigned long flags;
>> +
>> mutex_lock(&devfreq_list_lock);
>> if (IS_ERR(find_device_devfreq(devfreq->dev.parent))) {
>> mutex_unlock(&devfreq_list_lock);
>> @@ -400,6 +406,10 @@ static void _remove_devfreq(struct devfreq *devfreq, bool skip)
>> devfreq->governor->event_handler(devfreq,
>> DEVFREQ_GOV_STOP, NULL);
>>
>> + spin_lock_irqsave(&devfreq->dev.parent->power.lock, flags);
>> + devfreq->dev.parent->power.devfreq = NULL;
>> + spin_unlock_irqrestore(&devfreq->dev.parent->power.lock, flags);
>> +
>> if (devfreq->profile->exit)
>> devfreq->profile->exit(devfreq->dev.parent);
>>
>> @@ -442,6 +452,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
>> {
>> struct devfreq *devfreq;
>> struct devfreq_governor *governor;
>> + unsigned long flags;
>> int err = 0;
>>
>> if (!dev || !profile || !governor_name) {
>> @@ -476,6 +487,12 @@ struct devfreq *devfreq_add_device(struct device *dev,
>> devfreq->previous_freq = profile->initial_freq;
>> devfreq->data = data;
>> devfreq->nb.notifier_call = devfreq_notifier_call;
>> + devfreq->runtime_suspend = devfreq_runtime_suspend;
>> + devfreq->runtime_resume = devfreq_runtime_resume;
>> + spin_lock_irqsave(&dev->power.lock, flags);
>> + dev->power.devfreq = devfreq;
>> + spin_unlock_irqrestore(&dev->power.lock, flags);
>> +
>>
>> devfreq->trans_table = devm_kzalloc(dev, sizeof(unsigned int) *
>> devfreq->profile->max_state *
>> @@ -549,7 +566,7 @@ EXPORT_SYMBOL(devfreq_remove_device);
>> * (e.g., runtime_suspend, suspend) of the device driver that
>> * holds the devfreq.
>> */
>> -int devfreq_suspend_device(struct devfreq *devfreq)
>> +static int devfreq_suspend_device(struct devfreq *devfreq)
>> {
>> if (!devfreq)
>> return -EINVAL;
>> @@ -560,7 +577,6 @@ int devfreq_suspend_device(struct devfreq *devfreq)
>> return devfreq->governor->event_handler(devfreq,
>> DEVFREQ_GOV_SUSPEND, NULL);
>> }
>> -EXPORT_SYMBOL(devfreq_suspend_device);
>>
>> /**
>> * devfreq_resume_device() - Resume devfreq of a device.
>> @@ -570,7 +586,7 @@ EXPORT_SYMBOL(devfreq_suspend_device);
>> * (e.g., runtime_resume, resume) of the device driver that
>> * holds the devfreq.
>> */
>> -int devfreq_resume_device(struct devfreq *devfreq)
>> +static int devfreq_resume_device(struct devfreq *devfreq)
>> {
>> if (!devfreq)
>> return -EINVAL;
>> @@ -581,7 +597,52 @@ int devfreq_resume_device(struct devfreq *devfreq)
>> return devfreq->governor->event_handler(devfreq,
>> DEVFREQ_GOV_RESUME, NULL);
>> }
>> -EXPORT_SYMBOL(devfreq_resume_device);
>> +
>> +/**
>> + * devfreq_runtime_suspend() - Suspend devfreq of a device.
>> + * @dev: the device associated with devfreq
>> + *
>> + * This function is intended to be called by the runtime-pm
>> + * core when the device associated with devfreq is
>> + * runtime suspended.
>> + */
>> +static void devfreq_runtime_suspend(struct device *dev)
>> +{
>> + struct devfreq *devfreq;
>> + int err;
>> +
>> + mutex_lock(&devfreq_list_lock);
>> + devfreq = find_device_devfreq(dev);
>> + mutex_unlock(&devfreq_list_lock);
>> +
>> + err = devfreq_suspend_device(devfreq);
>> + if (err)
>> + dev_err(dev, "devfreq runtime suspend failed with (%d) error\n",
>> + err);
>> +}
>> +
>> +/**
>> + * devfreq_runtime_resume() - Resume devfreq of a device.
>> + * @dev: the device associated with devfreq
>> + *
>> + * This function is intended to be called by the runtime-pm
>> + * core when the device associated with devfreq is
>> + * runtime resumed.
>> + */
>> +static void devfreq_runtime_resume(struct device *dev)
>> +{
>> + struct devfreq *devfreq;
>> + int err;
>> +
>> + mutex_lock(&devfreq_list_lock);
>> + devfreq = find_device_devfreq(dev);
>> + mutex_unlock(&devfreq_list_lock);
>> +
>> + err = devfreq_resume_device(devfreq);
>> + if (err)
>> + dev_err(dev, "devfreq runtime resume failed with (%d) error\n",
>> + err);
>> +}
>>
>> /**
>> * devfreq_add_governor() - Add devfreq governor
>> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
>> index 5f1ab92..669368b 100644
>> --- a/include/linux/devfreq.h
>> +++ b/include/linux/devfreq.h
>> @@ -140,6 +140,8 @@ struct devfreq_governor {
>> * @trans_table: Statistics of devfreq transitions
>> * @time_in_state: Statistics of devfreq states
>> * @last_stat_updated: The last time stat updated
>> + * @runtime_suspend: func to runtime suspend devfreq from runtime core
>> + * @runtime_resume: func to runtime resume devfreq from runtime core
>> *
>> * This structure stores the devfreq information for a give device.
>> *
>> @@ -173,6 +175,8 @@ struct devfreq {
>> unsigned int *trans_table;
>> unsigned long *time_in_state;
>> unsigned long last_stat_updated;
>> + void (*runtime_suspend)(struct device *dev);
>> + void (*runtime_resume)(struct device *dev);
>> };
>>
>> #if defined(CONFIG_PM_DEVFREQ)
>> @@ -182,10 +186,6 @@ extern struct devfreq *devfreq_add_device(struct device *dev,
>> void *data);
>> extern int devfreq_remove_device(struct devfreq *devfreq);
>>
>> -/* Supposed to be called by PM_SLEEP/PM_RUNTIME callbacks */
>> -extern int devfreq_suspend_device(struct devfreq *devfreq);
>> -extern int devfreq_resume_device(struct devfreq *devfreq);
>> -
>> /* Helper functions for devfreq user device driver with OPP. */
>> extern struct opp *devfreq_recommended_opp(struct device *dev,
>> unsigned long *freq, u32 flags);
>> @@ -228,16 +228,6 @@ static inline int devfreq_remove_device(struct devfreq *devfreq)
>> return 0;
>> }
>>
>> -static inline int devfreq_suspend_device(struct devfreq *devfreq)
>> -{
>> - return 0;
>> -}
>> -
>> -static inline int devfreq_resume_device(struct devfreq *devfreq)
>> -{
>> - return 0;
>> -}
>> -
>> static inline struct opp *devfreq_recommended_opp(struct device *dev,
>> unsigned long *freq, u32 flags)
>> {
>> diff --git a/include/linux/pm.h b/include/linux/pm.h
>> index 03d7bb1..734449c 100644
>> --- a/include/linux/pm.h
>> +++ b/include/linux/pm.h
>> @@ -40,6 +40,7 @@ extern void (*pm_power_off_prepare)(void);
>> */
>>
>> struct device;
>> +struct devfreq;
>>
>> #ifdef CONFIG_PM
>> extern const char power_group_name[]; /* = "power" */
>> @@ -549,6 +550,7 @@ struct dev_pm_info {
>> #endif
>> struct pm_subsys_data *subsys_data; /* Owned by the subsystem. */
>> struct dev_pm_qos *qos;
>> + struct devfreq *devfreq; /* device devfreq */
>> };
>>
>> extern void update_pm_runtime_accounting(struct device *dev);
--
Regards,
Rajagopal
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