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SubjectRe: [PATCH 3/3] PM / devfreq: account suspend/resume for stats
From
On Tue, Jan 15, 2013 at 8:46 PM, Rajagopal Venkat
<rajagopal.venkat@linaro.org> wrote:
> On 14 January 2013 20:18, MyungJoo Ham <myungjoo.ham@samsung.com> wrote:
>> On Tue, Jan 8, 2013 at 2:50 PM, Rajagopal Venkat
>> <rajagopal.venkat@linaro.org> wrote:
>>> devfreq stats is not taking device suspend and resume into
>>> account. Fix it.
>>>
>>> Signed-off-by: Rajagopal Venkat <rajagopal.venkat@linaro.org>
>>
>> With monitor_suspend(), we are suspending the DVFS mechanism of a
>> device, not the device itself.
>>
>> Thus, the device may keep its frequency running and we may assume that
>> the frequency is constant as the DVFS mechanism is in suspend.
>>
>> Why do you want to stop the statistics as well?
>>
>
> There seems to be misunderstanding of devfreq_monitor_suspend() and
> devfreq_monitor_resume() apis usage.
>
> Typically devfreq_monitor_suspend() would be called to suspend the device
> devfreq when device is entering idle state by powering off(clocks and voltage).
> When device itself is off, it's incorrect to allow stats to continue.

Ah.. yes... you're right. It is meant to be called by suspend of
pm-sleep or pm-suspend.
This will be applied soon.


Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com>

>
>>
>>
>> Again, as in the other patch, this is about the semantics of the
>> "devfreq statistics".
>>
>> It does not seem to be a problem of which is correct and which is not,
>> but it seems to be a problem of which is more convenient.
>>
>> Could you please give me some cases where your semantics is more helpful?
>
> When gpu is powered off, gpu devfreq should be suspended and hence the stats.



>
>>
>>
>>
>> I've been using the stat feature like this:
>>
>> # cat stat; run benchmark; cat stat
>> and look at the differences with any ops done during "run benchmark".
>>
>>
>>
>> Cheers,
>> MyungJoo.
>>
>>> ---
>>> drivers/devfreq/devfreq.c | 15 ++++++++++++---
>>> 1 file changed, 12 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>>> index 2843a22..4c50235 100644
>>> --- a/drivers/devfreq/devfreq.c
>>> +++ b/drivers/devfreq/devfreq.c
>>> @@ -297,6 +297,7 @@ void devfreq_monitor_suspend(struct devfreq *devfreq)
>>> return;
>>> }
>>>
>>> + devfreq_update_status(devfreq, devfreq->previous_freq);
>>> devfreq->stop_polling = true;
>>> mutex_unlock(&devfreq->lock);
>>> cancel_delayed_work_sync(&devfreq->work);
>>> @@ -313,6 +314,8 @@ EXPORT_SYMBOL(devfreq_monitor_suspend);
>>> */
>>> void devfreq_monitor_resume(struct devfreq *devfreq)
>>> {
>>> + unsigned long freq;
>>> +
>>> mutex_lock(&devfreq->lock);
>>> if (!devfreq->stop_polling)
>>> goto out;
>>> @@ -321,8 +324,14 @@ void devfreq_monitor_resume(struct devfreq *devfreq)
>>> devfreq->profile->polling_ms)
>>> queue_delayed_work(devfreq_wq, &devfreq->work,
>>> msecs_to_jiffies(devfreq->profile->polling_ms));
>>> +
>>> + devfreq->last_stat_updated = jiffies;
>>> devfreq->stop_polling = false;
>>>
>>> + if (devfreq->profile->get_cur_freq &&
>>> + !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
>>> + devfreq->previous_freq = freq;
>>> +
>>> out:
>>> mutex_unlock(&devfreq->lock);
>>> }
>>> @@ -931,11 +940,11 @@ static ssize_t show_trans_table(struct device *dev, struct device_attribute *att
>>> {
>>> struct devfreq *devfreq = to_devfreq(dev);
>>> ssize_t len;
>>> - int i, j, err;
>>> + int i, j;
>>> unsigned int max_state = devfreq->profile->max_state;
>>>
>>> - err = devfreq_update_status(devfreq, devfreq->previous_freq);
>>> - if (err)
>>> + if (!devfreq->stop_polling &&
>>> + devfreq_update_status(devfreq, devfreq->previous_freq))
>>> return 0;
>>>
>>> len = sprintf(buf, " From : To\n");
>>> --
>>> 1.7.10.4
>>>
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe linux-pm" in
>>> the body of a message to majordomo@vger.kernel.org
>>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>>
>>
>>
>> --
>> MyungJoo Ham, Ph.D.
>> Mobile Software Platform Lab, DMC Business, Samsung Electronics
>
>
>
> --
> Regards,
> Rajagopal



--
MyungJoo Ham, Ph.D.
System S/W Lab, S/W Center, Samsung Electronics


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