linux-kernel - Re: [PATCH v3 5/7] cpufreq: add function to get the hardware max frequency

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Message-ID: <cf821516-e66b-94d4-ee63-5f94602a7cff@arm.com>
Date:   Thu, 13 Feb 2020 15:22:11 +0000
From:   Valentin Schneider <valentin.schneider@....com>
To:     Ionela Voinescu <ionela.voinescu@....com>
Cc:     catalin.marinas@....com, will@...nel.org, mark.rutland@....com,
        maz@...nel.org, suzuki.poulose@....com, sudeep.holla@....com,
        lukasz.luba@....com, rjw@...ysocki.net, peterz@...radead.org,
        mingo@...hat.com, vincent.guittot@...aro.org,
        viresh.kumar@...aro.org, linux-arm-kernel@...ts.infradead.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org
Subject: Re: [PATCH v3 5/7] cpufreq: add function to get the hardware max
 frequency

On 2/13/20 12:59 PM, Ionela Voinescu wrote:
>> What about intel_pstate / turbo stuff? IIRC one of Giovanni's issues was that
>> turbo freq is not always reported as the max freq. Dunno if we can do
>> anything about it; at the very least maybe document the caveat?
>>
> 
> Okay, I can add details in the description in regards to potential
> reasons to overwrite this function. But basically this is one of the
> reasons for making this a weak function. The best information we can
> generically get for maximum hardware frequency is cpuinfo.max_freq.
> But if platforms have the possibility to obtain this differently from
> either hardware or firmware they can overwrite this.
> 

Right, that would be handled by a different implementation of
that function, so this wasn't too relevant of a comment. Sorry!