linux-kernel - Re: [PATCH 2/2] cpufreq: CPPC: Fix error handling in cppc_scale_freq

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Message-ID: <CAFivqmLr_0BDkMhD4o6box3k9ouKek8pnY7aHX36h1Q9TaT_HA@mail.gmail.com>
Date: Fri, 1 Aug 2025 01:58:32 -0700
From: Prashant Malani <pmalani@...gle.com>
To: Jie Zhan <zhanjie9@...ilicon.com>
Cc: Viresh Kumar <viresh.kumar@...aro.org>, Bowen Yu <yubowen8@...wei.com>, rafael@...nel.org, 
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org, linuxarm@...wei.com, 
	jonathan.cameron@...wei.com, lihuisong@...wei.com, zhenglifeng1@...wei.com, 
	Beata Michalska <beata.michalska@....com>, Ionela Voinescu <ionela.voinescu@....com>
Subject: Re: [PATCH 2/2] cpufreq: CPPC: Fix error handling in cppc_scale_freq_workfn()

Hi Jie,

On Thu, 31 Jul 2025 at 01:32, Jie Zhan <zhanjie9@...ilicon.com> wrote:
>
>
>
> On 31/07/2025 06:34, Prashant Malani wrote:
>
> Hi Prashant,
>
> The perf counters could return 0 when a CPU is enters a low-power idle
> state, e.g. reset or powered down, and the perf counters are in the system
> memory space (the target CPU is not woken up unfortunately).
>

Thanks for the clarification. Reset and powered down are not typically
considered "low-power idle states".
Please re-word your commit message to specifically call out the "reset and
powered-down" CPU states.

This begs the question: why is this work function being scheduled
for CPUs that are in reset or offline/powered-down at all?
IANAE but it sounds like it would be better to add logic to ensure this
work function doesn't get scheduled/executed for CPUs that
are truly offline/powered-down or in reset.

BR,

-- 
-Prashant