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Message-id: <5BF61A7A.1060805@samsung.com>
Date: Thu, 22 Nov 2018 11:54:50 +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
On 2018년 11월 22일 11:52, 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.
>
>>
>> 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.
>
>> +{
>> + 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;
>> +}
You can change the devfreq_set_target as following:
static int devfreq_set_target(struct devfreq *devfreq, unsigned long new_freq,
- unsigned long *prev_freq, u32 flags)
+ u32 flags)
{
struct devfreq_freqs freqs;
unsigned long cur_freq;
@@ -319,7 +319,9 @@ static int devfreq_set_target(struct devfreq *devfreq, unsigned long new_freq,
"Couldn't update frequency transition information.\n");
devfreq->previous_freq = new_freq;
- *prev_freq = cur_freq;
But, you have to add following new code on patch3 instead of patch2.
+
+ if (devfreq->suspend_freq)
+ devfreq->resume_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.
>
>>
>> - 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);
>>
>>
>
>
--
Best Regards,
Chanwoo Choi
Samsung Electronics
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