linux-kernel - Re: [PATCH] PM / devfreq: Remove redundant frequency adjustment from governors

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Message-id: <5AFE0DB6.1060801@samsung.com>
Date:   Fri, 18 May 2018 08:18:14 +0900
From:   Chanwoo Choi <cw00.choi@...sung.com>
To:     Matthias Kaehlcke <mka@...omium.org>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Brian Norris <briannorris@...omium.org>,
        Douglas Anderson <dianders@...omium.org>
Subject: Re: [PATCH] PM / devfreq: Remove redundant frequency adjustment
 from governors

On 2018년 05월 18일 07:41, Matthias Kaehlcke wrote:
> On Wed, May 16, 2018 at 02:10:51PM -0700, Matthias Kaehlcke wrote:
>> The performance, powersave, simpleondemand and userspace governors
>> determine a target frequency and then adjust it according to the
>> df->min/max_freq limits that might have been set by user space. This
>> adjustment is redundant, it is done in update_devfreq() for any
>> governor, right after governor->get_target_freq().
>>
>> Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
>> ---
>>  drivers/devfreq/governor_performance.c    | 10 ++--------
>>  drivers/devfreq/governor_powersave.c      |  5 -----
>>  drivers/devfreq/governor_simpleondemand.c |  7 +------
>>  drivers/devfreq/governor_userspace.c      | 16 ++++------------
>>  4 files changed, 7 insertions(+), 31 deletions(-)
>>
>> diff --git a/drivers/devfreq/governor_performance.c b/drivers/devfreq/governor_performance.c
>> index 4d23ecfbd948..31ee30622c00 100644
>> --- a/drivers/devfreq/governor_performance.c
>> +++ b/drivers/devfreq/governor_performance.c
>> @@ -16,14 +16,8 @@
>>  static int devfreq_performance_func(struct devfreq *df,
>>  				    unsigned long *freq)
>>  {
>> -	/*
>> -	 * target callback should be able to get floor value as
>> -	 * said in devfreq.h
>> -	 */
>> -	if (!df->max_freq)
>> -		*freq = UINT_MAX;
>> -	else
>> -		*freq = df->max_freq;
>> +	*freq = UINT_MAX;
>> +
>>  	return 0;
>>  }
> 
> For the record, the frequency adjustment in update_devfreq() is
> currently broken for df->max_freq == 0:
> 
> https://patchwork.kernel.org/patch/10407827/

Why don't you send patch set? It is very difficult to track
the history and a correlation between patches. Usually, if patches
have the dependency between patches, send the patch set with cover-letter.

-- 
Best Regards,
Chanwoo Choi
Samsung Electronics