[PATCH v1 1/2] PM/devfreq: add suspend frequency support
myungjoo.ham at samsung.com
Tue Nov 22 04:48:14 PST 2016
On Thu, Nov 3, 2016 at 4:03 PM, hl <hl at rock-chips.com> wrote:
> Hi MyungJoo Ham,
> On 2016年11月02日 14:35, MyungJoo Ham 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).
>>> Change-Id: Iaa0d3848d63d9ce03f65ea76f263e4685a4c295e
>>> Signed-off-by: Lin Huang <hl at rock-chips.com>
>>> drivers/devfreq/devfreq.c | 17 ++++++++++++++++-
>>> include/linux/devfreq.h | 9 +++++++++
>>> 2 files changed, 25 insertions(+), 1 deletion(-)
>>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>>> index bf3ea76..d1152eb 100644
>>> --- a/drivers/devfreq/devfreq.c
>>> +++ b/drivers/devfreq/devfreq.c
>>> @@ -364,7 +364,10 @@ void devfreq_monitor_suspend(struct devfreq
>>> - devfreq_update_status(devfreq, devfreq->previous_freq);
>>> + if (devfreq->suspend_freq)
>>> + devfreq_update_status(devfreq, devfreq->suspend_freq);
>>> + else
>>> + devfreq_update_status(devfreq, devfreq->previous_freq);
>> This is incorrect.
>> devfreq_update_status is to record the statistics.
>> This code intends to record the current status before entering suspend;
>> thus you should not record "suspend_freq" here.
>> If you really need to record the frequency during suspended state
>> for the statistics, you need to do that at resume; however, I object to
>> that idea either.
>> If you really want to set a predefined suspend-to-RAM mode frequency,
>> (probably because of HW instability during resume process)
>> you need to update, not udpate_status (statistics).
> Thanks for pointing it, but if i use update_devfreq(), it can not specify
> frequency, it call the get_target_freq() to get the frequency and setting,
> use now devfreq framework, it seems hard to set the specific freqeuency
> when suspend. Do you have any idea, thanks.
It appears that we need to set the frequency directly with target() function
at suspend/resume after it is assured that related routines are
Plus, you might need to consider using devfreq_suspend/resume_device instead
of monitor. monitor functions are for the governor-specific behaviors.
You'll need such capabilities regardless of governors. (even userspace-governor
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MyungJoo Ham, Ph.D.
Frontier CS Lab, S/W Center, Samsung Electronics
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