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| Started by | MyungJoo Ham <myungjoo.ham@samsung.com> |
|---|---|
| First post | 2015-11-23 10:20 +0100 |
| Last post | 2015-11-24 14:50 +0100 |
| Articles | 2 — 2 participants |
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Re: Re: Re: [PATCH 6/6] PM / devfreq: Set the min_freq and max_freq of devfreq device MyungJoo Ham <myungjoo.ham@samsung.com> - 2015-11-23 10:20 +0100
Re: Re: Re: [PATCH 6/6] PM / devfreq: Set the min_freq and max_freq of devfreq device Chanwoo Choi <cwchoi00@gmail.com> - 2015-11-24 14:50 +0100
| From | MyungJoo Ham <myungjoo.ham@samsung.com> |
|---|---|
| Date | 2015-11-23 10:20 +0100 |
| Subject | Re: Re: Re: [PATCH 6/6] PM / devfreq: Set the min_freq and max_freq of devfreq device |
| Message-ID | <qxVrZ-8gl-7@gated-at.bofh.it> |
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| From | Chanwoo Choi <cwchoi00@gmail.com> |
|---|---|
| Date | 2015-11-24 14:50 +0100 |
| Subject | Re: Re: Re: [PATCH 6/6] PM / devfreq: Set the min_freq and max_freq of devfreq device |
| Message-ID | <qym8N-jw-3@gated-at.bofh.it> |
| In reply to | #1275149 |
On Mon, Nov 23, 2015 at 6:13 PM, MyungJoo Ham <myungjoo.ham@samsung.com> wrote: >> 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. >> > > Even without the side effect, what would be the meaning of initializing > min/max-freq to the device min/max capabilities when the users may > override it with arbitrary lower/higher values? Yes, the user can update min_freq/max_freq because this attribute have the writable permission. The users might think that min_freq/max_freq provide the users with the minimum and maximum frequency. because CPUFREQ show the frequency on scaling_min_freq / scaling_max_freq. But, right after kernel booting, min_freq/max_freq is zero (0). I think that it cause the confusion for users. Regards, Chanwoo Choi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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