linux-kernel - Re: [PATCH v6 1/2] PM / Domains: Add support for 'required-opps' to set default perf state

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Message-ID: <85e207da-51ca-bb25-4de6-90b287fa31f8@gmail.com>
Date:   Thu, 12 Aug 2021 05:28:13 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Rajendra Nayak <rnayak@...eaurora.org>, ulf.hansson@...aro.org,
        bjorn.andersson@...aro.org, viresh.kumar@...aro.org
Cc:     linux-pm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        swboyd@...omium.org, rojay@...eaurora.org, stephan@...hold.net
Subject: Re: [PATCH v6 1/2] PM / Domains: Add support for 'required-opps' to
 set default perf state

11.08.2021 22:48, Dmitry Osipenko пишет:
> 11.08.2021 12:45, Rajendra Nayak пишет:
>>>
>>> If you have more than one power domain, then this will override the
>>> pstate which was set for a previous domain. This code doesn't feel solid
>>> to me, at least a clarifying comment is needed about how it's supposed
>>> to work.
>>
>> I don't quite understand the concern here, this should work with devices
>> having multiple power-domains as well. __genpd_dev_pm_attach gets called
>> once per power-domain, and we use the index above to identify the
>> power-domain.
> 
> The domain core code supports only one domain per device, see what
> genpd_set_performance_state() does. This means that the second domain
> will set the state of the *first* domain, which doesn't make sense. The
> genpd_set_performance_state() will actually fail with -ENODEV for all
> domains if you will try to do that.
> 

I confused the base device with the virtual device there, looks like it
should be okay then.