Re: Re: [PATCH 6/6] PM / devfreq: Set the min_freq and max_freq of devfreq device

Re: Re: [PATCH 6/6] PM / devfreq: Set the min_freq and max_freq of devfreq device

[MyungJoo Ham]

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[]
> > 
> > The value 0 is used for min/max_freq to declare
> > that min/max_freq is deactivated. Therefore, it is not
> > required to do so; they are not intended to show the hardware
> > configuration as well.
> 
> This case consider the devfreq device using OPP because devfreq_set_freq_table()
> get the number of OPP entry in OPP list before setting the min_freq/max_freq.
> If the devfreq device don't use the OPP entry, devfreq_set_freq_table()
> will return without any operation.
> 
> IMHO, when devfreq device uses the OPP table including the frequency,
> min_freq/max_freq should show the correct value as CPUFREQ framework.
> 

The side effect of this patch shows up when opp_disable() and opp_enable()
are used.

For example,
1. dev->opp_disable(2GHz); /* 2GHz is the fastest and 1.6 is the second */
2. init devfreq of dev; /* setting max_freq @ 1.6G by this patch */
3. dev->opp_enable(2GHz);
4. 2GHz is still not active because max_freq is now 1.6GHz.

Cheers,
MyungJoo.


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Re: Re: [PATCH 6/6] PM / devfreq: Set the min_freq and max_freq of devfreq device

[Chanwoo Choi]

On Mon, Nov 23, 2015 at 4:21 PM, MyungJoo Ham <myungjoo.ham@samsung.com> wrote:
> []
>> >
>> > The value 0 is used for min/max_freq to declare
>> > that min/max_freq is deactivated. Therefore, it is not
>> > required to do so; they are not intended to show the hardware
>> > configuration as well.
>>
>> This case consider the devfreq device using OPP because devfreq_set_freq_table()
>> get the number of OPP entry in OPP list before setting the min_freq/max_freq.
>> If the devfreq device don't use the OPP entry, devfreq_set_freq_table()
>> will return without any operation.
>>
>> IMHO, when devfreq device uses the OPP table including the frequency,
>> min_freq/max_freq should show the correct value as CPUFREQ framework.
>>
>
> The side effect of this patch shows up when opp_disable() and opp_enable()
> are used.

Ah. You're right.
I was not considering the the case of using opp_disable() and opp_enable().
I'll consider it again including the usage case of opp_diable/opp_enable.

Regards,
Chanwoo Choi