Re: [PATCH v4] PM/devfreq: add suspend frequency support

[hl <hl@rock-chips.com>]

Hi Chanwoo Choi,

On 2016年11月08日 17:32, Chanwoo Choi wrote:
> Hi Lin,
>
> On 2016년 11월 08일 18:11, Lin Huang wrote:
>> Add suspend frequency support and if needed set it to
>> the frequency obtained from the suspend opp (can be defined
>> using opp-v2 bindings and is optional).
>>
>> Signed-off-by: Lin Huang <hl@rock-chips.com>
>> ---
>> Changes in v2:
>> - use update_devfreq() instead devfreq_update_status()
>> Changes in v3:
>> - fix build error
>> Changes in v4:
>> - move dev_pm_opp_get_suspend_opp() to devfreq_add_device()
>>
>>   drivers/devfreq/devfreq.c                 | 15 +++++++++++++--
>>   drivers/devfreq/governor_simpleondemand.c |  9 +++++++++
>>   include/linux/devfreq.h                   |  9 +++++++++
>>   3 files changed, 31 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>> index bf3ea76..d9d56e1 100644
>> --- a/drivers/devfreq/devfreq.c
>> +++ b/drivers/devfreq/devfreq.c
>> @@ -363,7 +363,10 @@ void devfreq_monitor_suspend(struct devfreq *devfreq)
>>   		mutex_unlock(&devfreq->lock);
>>   		return;
>>   	}
>> -
>> +	if (devfreq->suspend_freq) {
>> +		update_devfreq(devfreq);
>> +		devfreq->suspend_flag = true;
> You don't need the additional variable (devfreq->suspend_flag).
> When adding the devfreq on devfreq_add_device(),
> you can initialize the devfreq->suspend_freq as zero(0).
>
> You can check whether devfreq->suspend_freq is 0 or not
> without the new suspend_flag.
>
>> +	}
>>   	devfreq_update_status(devfreq, devfreq->previous_freq);
>>   	devfreq->stop_polling = true;
>>   	mutex_unlock(&devfreq->lock);
>> @@ -394,7 +397,8 @@ void devfreq_monitor_resume(struct devfreq *devfreq)
>>   
>>   	devfreq->last_stat_updated = jiffies;
>>   	devfreq->stop_polling = false;
>> -
>> +	if (devfreq->suspend_freq)
>> +		devfreq->suspend_flag = false;
> ditto. You don't need to add this code.
>
>>   	if (devfreq->profile->get_cur_freq &&
>>   		!devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
>>   		devfreq->previous_freq = freq;
>> @@ -528,6 +532,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
>>   	struct devfreq *devfreq;
>>   	struct devfreq_governor *governor;
>>   	int err = 0;
>> +	struct dev_pm_opp *suspend_opp;
>>   
>>   	if (!dev || !profile || !governor_name) {
>>   		dev_err(dev, "%s: Invalid parameters.\n", __func__);
>> @@ -563,6 +568,12 @@ struct devfreq *devfreq_add_device(struct device *dev,
>>   	devfreq->data = data;
>>   	devfreq->nb.notifier_call = devfreq_notifier_call;
>>   
>> +	rcu_read_lock();
>> +	suspend_opp = dev_pm_opp_get_suspend_opp(dev);
>> +	if (suspend_opp)
>> +		devfreq->suspend_freq = dev_pm_opp_get_freq(suspend_opp);
>> +	rcu_read_unlock();
>> +
>>   	if (!devfreq->profile->max_state && !devfreq->profile->freq_table) {
>>   		mutex_unlock(&devfreq->lock);
>>   		devfreq_set_freq_table(devfreq);
>> diff --git a/drivers/devfreq/governor_simpleondemand.c b/drivers/devfreq/governor_simpleondemand.c
>> index ae72ba5..84b3ce1 100644
>> --- a/drivers/devfreq/governor_simpleondemand.c
>> +++ b/drivers/devfreq/governor_simpleondemand.c
>> @@ -29,6 +29,15 @@ static int devfreq_simple_ondemand_func(struct devfreq *df,
>>   	struct devfreq_simple_ondemand_data *data = df->data;
>>   	unsigned long max = (df->max_freq) ? df->max_freq : UINT_MAX;
>>   
>> +	/*
>> +	 * if devfreq in suspend status and have suspend_freq,
>> +	 * the frequency need to set to suspend_freq
>> +	 */
>> +	if (df->suspend_flag) {
>> +		*freq =	df->suspend_freq;
>> +		return 0;
>> +	}
> You can check it as following:
>
> 	if (df->suspend_freq != 0)
> 		*freq = df->suspend_freq;
If i do like this, it will always return suspend frequency, since 
devfreq->suspend_freq will be assigned value
if we define it on dts. But what we want is only in suspend status we 
return the suspend frequency.
>
>> +
>>   	err = devfreq_update_stats(df);
>>   	if (err)
>>   		return err;
>> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
>> index 2de4e2e..c463ae1 100644
>> --- a/include/linux/devfreq.h
>> +++ b/include/linux/devfreq.h
>> @@ -172,6 +172,7 @@ struct devfreq {
>>   	struct delayed_work work;
>>   
>>   	unsigned long previous_freq;
>> +	unsigned long suspend_freq;
>>   	struct devfreq_dev_status last_status;
>>   
>>   	void *data; /* private data for governors */
>> @@ -179,6 +180,7 @@ struct devfreq {
>>   	unsigned long min_freq;
>>   	unsigned long max_freq;
>>   	bool stop_polling;
>> +	bool suspend_flag;
> You don't need to add new variable.
>
>>   
>>   	/* information for device frequency transition */
>>   	unsigned int total_trans;
>> @@ -214,6 +216,8 @@ extern int devfreq_resume_device(struct devfreq *devfreq);
>>   /* Helper functions for devfreq user device driver with OPP. */
>>   extern struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
>>   					   unsigned long *freq, u32 flags);
>> +extern void devfreq_opp_get_suspend_opp(struct device *dev,
>> +					struct devfreq *devfreq);
> Why do you need this function? Also, this patch don't include the body
> of devfreq_opp_get_suspend_opp() function.
Oh, forget to delete it, sorry about that.
>
>>   extern int devfreq_register_opp_notifier(struct device *dev,
>>   					 struct devfreq *devfreq);
>>   extern int devfreq_unregister_opp_notifier(struct device *dev,
>> @@ -348,6 +352,11 @@ static inline struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
>>   	return ERR_PTR(-EINVAL);
>>   }
>>   
>> +static inline void devfreq_opp_get_suspend_opp(struct device *dev,
>> +					       struct devfreq *devfreq)
>> +{
>> +}
>> +
>>   static inline int devfreq_register_opp_notifier(struct device *dev,
>>   					 struct devfreq *devfreq)
>>   {
>>

-- 
Lin Huang



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