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Message-id: <5BF73FA9.7010402@samsung.com>
Date: Fri, 23 Nov 2018 08:45:45 +0900
From: Chanwoo Choi <cw00.choi@...sung.com>
To: Lukasz Luba <l.luba@...tner.samsung.com>,
linux-arm-kernel@...ts.infradead.org,
linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-pm@...r.kernel.org, devicetree@...r.kernel.org
Cc: tjakobi@...h.uni-bielefeld.de, myungjoo.ham@...sung.com,
kyungmin.park@...sung.com, rjw@...ysocki.net, len.brown@...el.com,
pavel@....cz, gregkh@...uxfoundation.org, keescook@...omium.org,
anton@...msg.org, ccross@...roid.com, tony.luck@...el.com,
robh+dt@...nel.org, mark.rutland@....com, kgene@...nel.org,
krzk@...nel.org, m.szyprowski@...sung.com, b.zolnierkie@...sung.com
Subject: Re: [PATCH 2/6] devfreq: refactor set_target frequency function
Hi Lukasz,
On 2018년 11월 22일 19:40, Lukasz Luba wrote:
> Hi Chanwoo Choi
>
> On 11/22/18 3:52 AM, Chanwoo Choi wrote:
>> On 2018년 11월 22일 03:01, Lukasz Luba wrote:
>>> The refactoring is needed for the new client in devfreq: suspend.
>>> To avoid code duplication, move it to the new local function
>>> devfreq_set_target.
>>>
>>> The patch draws on Tobias Jakobi's work posted ~2 years ago, who tried to
>>> solve issue with devfreq device's frequency during suspend/resume.
>>> During the discussion on LKML some corner cases and comments appeared
>>> related to the design. This patch address them keeping in mind suggestions
>>> from Chanwoo Choi.
>>
>> As I commented on patch1, please remove it.
> OK
>>
>>>
>>> Suggested-by: Tobias Jakobi <tjakobi@...h.uni-bielefeld.de>
>>> Suggested-by: Chanwoo Choi <cw00.choi@...sung.com>
>>> Signed-off-by: Lukasz Luba <l.luba@...tner.samsung.com>
>>> ---
>>> drivers/devfreq/devfreq.c | 62 ++++++++++++++++++++++++++++-------------------
>>> 1 file changed, 37 insertions(+), 25 deletions(-)
>>>
>>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>>> index e20e7e4..cf9c643 100644
>>> --- a/drivers/devfreq/devfreq.c
>>> +++ b/drivers/devfreq/devfreq.c
>>> @@ -285,6 +285,42 @@ static int devfreq_notify_transition(struct devfreq *devfreq,
>>> return 0;
>>> }
>>>
>>> +static int devfreq_set_target(struct devfreq *devfreq, unsigned long new_freq,
>>> + unsigned long *prev_freq, u32 flags)
>>
>> Please remove the unused space in front of 'unsigned long *prev_freq'.
>> Use tab only for indentation.
> OK
>>
>>> +{
>>> + struct devfreq_freqs freqs;
>>> + unsigned long cur_freq;
>>> + int err = 0;
>>> +
>>> + if (devfreq->profile->get_cur_freq)
>>> + devfreq->profile->get_cur_freq(devfreq->dev.parent, &cur_freq);
>>> + else
>>> + cur_freq = devfreq->previous_freq;
>>> +
>>> + freqs.old = cur_freq;
>>> + freqs.new = new_freq;
>>> + devfreq_notify_transition(devfreq, &freqs, DEVFREQ_PRECHANGE);
>>> +
>>> + err = devfreq->profile->target(devfreq->dev.parent, &new_freq, flags);
>>> + if (err) {
>>> + freqs.new = cur_freq;
>>> + devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
>>> + return err;
>>> + }
>>> +
>>> + freqs.new = new_freq;
>>> + devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
>>> +
>>> + if (devfreq_update_status(devfreq, new_freq))
>>> + dev_err(&devfreq->dev,
>>> + "Couldn't update frequency transition information.\n");
>>> +
>>> + devfreq->previous_freq = new_freq;
>>> + *prev_freq = cur_freq;
>>> +
>>> + return err;
>>> +}
>>> +
>>> /* Load monitoring helper functions for governors use */
>>>
>>> /**
>>> @@ -296,7 +332,6 @@ static int devfreq_notify_transition(struct devfreq *devfreq,
>>> */
>>> int update_devfreq(struct devfreq *devfreq)
>>> {
>>> - struct devfreq_freqs freqs;
>>> unsigned long freq, cur_freq, min_freq, max_freq;
>>
>>
>> cur_freq is not used after modification. Remove it.
>>
>>> int err = 0;
>>> u32 flags = 0;
>>> @@ -333,31 +368,8 @@ int update_devfreq(struct devfreq *devfreq)
>>> flags |= DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use LUB */
>>> }
>>>
>>> - if (devfreq->profile->get_cur_freq)
>>> - devfreq->profile->get_cur_freq(devfreq->dev.parent, &cur_freq);
>>> - else
>>> - cur_freq = devfreq->previous_freq;
>>> -
>>> - freqs.old = cur_freq;
>>> - freqs.new = freq;
>>> - devfreq_notify_transition(devfreq, &freqs, DEVFREQ_PRECHANGE);
>>> + return devfreq_set_target(devfreq, freq, &cur_freq, flags);
>>
>> You get the 'cur_freq' from devfreq_set_taget() for devfreq_suspend_device() on patch3.
>> But, update_devfreq() and devfreq_resume_device() don't use the 'cur_freq' value
>> from devfreq_set_target().
>>
>> Instead, getting 'cur_freq' for 'devfreq->resume_freq' in the devfreq_set_target().
>> Please remove the 'cur_freq' parameter from devfreq_set_target.
>
> I can remove the 3rd parameter from devfreq_set_target(),
> but it implies that patch 1 and 3 cannot be merged. The function
> devfreq_set_target will use 'devfreq->resume_freq' so it must be in
> devfreq struct.
> So, in v2 version there will be still 6 patches, with the 1st patch
> defining needed fields in devfreq struct.
> Do you agree for that?
So, I replied again as following on my other reply[1] of patch2:
[1] https://lkml.org/lkml/2018/11/22/507
But, you have to add following new code on patch3 instead of patch2.
patch2 doesn't contain the following codes and then
patch3 adds 'resume_freq' variable and adds the following code on patch3.
+
+ if (devfreq->suspend_freq)
+ devfreq->resume_freq = cur_freq;
>
>>
>>>
>>> - err = devfreq->profile->target(devfreq->dev.parent, &freq, flags);
>>> - if (err) {
>>> - freqs.new = cur_freq;
>>> - devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
>>> - return err;
>>> - }
>>> -
>>> - freqs.new = freq;
>>> - devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
>>> -
>>> - if (devfreq_update_status(devfreq, freq))
>>> - dev_err(&devfreq->dev,
>>> - "Couldn't update frequency transition information.\n");
>>> -
>>> - devfreq->previous_freq = freq;
>>> - return err;
>>> }
>>> EXPORT_SYMBOL(update_devfreq);
>>>
>>>
>>
>>
>
> Regards,
> Lukasz Luba
>
>
--
Best Regards,
Chanwoo Choi
Samsung Electronics
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