linux-kernel - Re: [PATCH 2/3] devfreq: mediatek: add mt8183 cci devfreq driver

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Message-ID: <7h7d808sti.fsf@baylibre.com>
Date:   Thu, 07 Apr 2022 14:52:25 -0700
From:   Kevin Hilman <khilman@...nel.org>
To:     Hsin-Yi Wang <hsinyi@...gle.com>,
        Tim Chang <jia-wei.chang@...iatek.com>
Cc:     MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Rob Herring <robh+dt@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>, linux-pm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        fan.chen@...iatek.com, louis.yu@...iatek.com,
        roger.lu@...iatek.com, Allen-yy.Lin@...iatek.com,
        Project_Global_Chrome_Upstream_Group@...iatek.com,
        Jia-Wei Chang <jia-wei.chang@...iatek.corp-partner.google.com>
Subject: Re: [PATCH 2/3] devfreq: mediatek: add mt8183 cci devfreq driver

Hsin-Yi Wang <hsinyi@...gle.com> writes:

> On Mon, Mar 7, 2022 at 8:32 PM Tim Chang <jia-wei.chang@...iatek.com> wrote:
>>
>> This adds a devfreq driver for the Cache Coherent Interconnect (CCI) of
>> the Mediatek MT8183.
>>
>> On mt8183 the cci is supplied by the same regulator as the little cores.
>> The driver is notified when the regulator voltage changes (driven by
>> cpufreq) and adjusts the cci frequency to the maximum possible value.
>>
>> Add need_voltage_tracking variable to platforma data. if true, it
>> indicates soc is required to realize the voltage tracking between
>> voltage of sram and voltage of cci by software approach. otherwise, the
>> voltage tracking is realized by hardware appraoch.
>>
>> Add the notifier to cci so that it could react after svs driver changes
>> opp table of cci.
>>
>> Signed-off-by: Jia-Wei Chang <jia-wei.chang@...iatek.corp-partner.google.com>

[...]

>> +
>> +       passive_data = devm_kzalloc(cci_dev, sizeof(struct devfreq_passive_data), GFP_KERNEL);
>> +       if (!passive_data) {
>> +               ret = -ENOMEM;
>> +               goto out_remove_opp_table;
>> +       }
>> +
>> +       passive_data->parent_type = CPUFREQ_PARENT_DEV;
>
> It's better to add a note below commit message to state that this
> series depends on
> https://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git/log/?h=devfreq-testing

Not only is this series dependent the previous series from Chanwoo, in
also fails to compile if CONFIG_DEVFREQ_GOV_PASSIVE is not enabled,
because CPUFREQ_PARENT_DEV defined inside of an #ifdef.

Please compile test this with and without CONFIG_DEVFREQ_GOV_PASSIVE
enabled.

Kevin