linux-kernel - Re: [PATCH v3 0/4] PM / devfreq: Add cpu based scaling support to passive governor

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Date:   Tue, 10 May 2022 18:08:22 +0900
From:   Chanwoo Choi <cwchoi00@...il.com>
To:     Chen-Yu Tsai <wenst@...omium.org>
Cc:     Linux PM list <linux-pm@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Johnson Wang <johnson.wang@...iatek.com>,
        Matthias Kaehlcke <mka@...omium.org>,
        jia-wei.chang@...iatek.com, andrew-sh.cheng@...iatek.com,
        hsinyi@...omium.org, Saravana Kannan <saravanak@...gle.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>
Subject: Re: [PATCH v3 0/4] PM / devfreq: Add cpu based scaling support to
 passive governor

Hi Chen-Yu,

On Tue, May 10, 2022 at 6:00 PM Chen-Yu Tsai <wenst@...omium.org> wrote:
>
> On Mon, May 9, 2022 at 8:03 PM Chanwoo Choi <cwchoi00@...il.com> wrote:
> >
> > The devfreq passive governor has already supported the devfreq parent device
> > for coupling the frequency change if some hardware have the constraints
> > such as power sharing and so on.
> >
> > Add cpu based scaling support to passive governor with required-opp property.
> > It uses the cpufreq notifier to catch the frequency change timing of cpufreq
> > and get the next frequency according to new cpu frequency by using required-opp
> > property. It is based on patch[1] and then just code clean-up by myself.
> >
> > Make the common code for both passive_devfreq and passive_cpufreq
> > parent type to remove the duplicate code.
> >
> > [1] [RFC,v2] PM / devfreq: Add cpu based scaling support to passive_governor
> > - https://lore.kernel.org/patchwork/patch/1101049/
> >
> > Changes from v2:
> > : https://patchwork.kernel.org/project/linux-pm/cover/20220507150145.531864-1-cw00.choi@samsung.com/
> > - Drop the following patch ("PM / devfreq: passive: Update frequency when start governor")
> > - Move p_data->this initialization into cpufreq_passive_regiser_notifier()
> >
> > Changes from v1:
> > : https://patchwork.kernel.org/project/linux-pm/cover/20210617060546.26933-1-cw00.choi@samsung.com/
> > - Rename cpu_data variable to parent_cpu_data to avoid build fail
> > - Use for_each_possible_cpu macro when register cpufreq transition notifier
> > - Add missing exception handling when cpufreq_passive_register_notifier is failed
> > - Keep cpufreq_policy for posible cpus instead of NR_CPU in order to avoid
> >   the memory waste when NR_CPU is too high.
> > - Add reviewed-by tag of Matthias Kaehlcke for patch1
> >
> >
> > Chanwoo Choi (3):
> >   PM / devfreq: Export devfreq_get_freq_range symbol within devfreq
> >   PM / devfreq: passive: Reduce duplicate code when passive_devfreq case
> >   PM / devfreq: passive: Keep cpufreq_policy for possible cpus
> >
> > Saravana Kannan (1):
> >   PM / devfreq: Add cpu based scaling support to passive governor
>
> Tested-by: Chen-Yu Tsai <wenst@...omium.org>
>
> on next-20220509 in conjunction with the MediaTek cpufreq [1], CCI devfreq [2]
> & SVS [3] series, as well as some fix-ups [4]. AFAICT the CCI devfreq device
> is reacting and making frequency changes.
>
>
> Regards
> ChenYu
>
> [1] https://lore.kernel.org/all/20220422075239.16437-1-rex-bc.chen@mediatek.com/
> [2] https://lore.kernel.org/all/20220408052150.22536-1-johnson.wang@mediatek.com/
> [3] https://lore.kernel.org/all/20220420102044.10832-1-roger.lu@mediatek.com/
> [4] https://github.com/wens/linux/commits/mt8183-cpufreq-cci-svs-test

Thanks for your test.

-- 
Best Regards,
Chanwoo Choi