linux-kernel - Re: [PATCH V4 4/5] soc: qcom: Introduce SCMI based Memlat (Memory Latency) governor

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <6356241e-6bfc-c4dc-1fbd-cd92f1b236ba@quicinc.com>
Date: Thu, 5 Dec 2024 15:47:14 +0530
From: Sibi Sankar <quic_sibis@...cinc.com>
To: <myungjoo.ham@...sung.com>,
        Dmitry Baryshkov
	<dmitry.baryshkov@...aro.org>,
        Kyungmin Park <Kyungmin.park@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Viresh Kumar <viresh.kumar@...aro.org>
CC: "sudeep.holla@....com" <sudeep.holla@....com>,
        "cristian.marussi@....com"
	<cristian.marussi@....com>,
        "andersson@...nel.org" <andersson@...nel.org>,
        "konrad.dybcio@...aro.org" <konrad.dybcio@...aro.org>,
        "robh+dt@...nel.org"
	<robh+dt@...nel.org>,
        "krzysztof.kozlowski+dt@...aro.org"
	<krzysztof.kozlowski+dt@...aro.org>,
        "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>,
        "linux-arm-msm@...r.kernel.org"
	<linux-arm-msm@...r.kernel.org>,
        "devicetree@...r.kernel.org"
	<devicetree@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>,
        "quic_rgottimu@...cinc.com"
	<quic_rgottimu@...cinc.com>,
        "quic_kshivnan@...cinc.com"
	<quic_kshivnan@...cinc.com>,
        "conor+dt@...nel.org" <conor+dt@...nel.org>,
        "arm-scmi@...r.kernel.org" <arm-scmi@...r.kernel.org>,
        Amir Vajid
	<avajid@...cinc.com>
Subject: Re: [PATCH V4 4/5] soc: qcom: Introduce SCMI based Memlat (Memory
 Latency) governor



On 11/15/24 06:08, MyungJoo Ham wrote:
>>
>> Hey Dmitry,
>>
>> Thanks for taking time to review the series.
>>
>> + Devfreq maintainers to comment (I thought you already added
>> them by name)
>>
>>
>> Hey MyungJoo/Kyungmin/Chanwoo,
>>
>> Can you weigh in here? Does it make sense to add a new
>> class of devfreq devices that don't have governors
>> associated with them just for them to export a few
>> essential data to userspace? In this scenario the
>> scaling algorithm is in a SCP and we just start
>> them from the kernel. We do have ways to get the
>> current frequency of various buses but does this
>> warrant adding a new class of governor less devices?
>>
>> -Sibi
> 
> If voltage/frequency is controlled by SCP
> (it's an SoC's internal hardware IP, right?),
> it's good to have a userspace governer
> with the driver not accepting updates from userspace.
> 
> E.g., Let "target" callback not update the frequency value,
>   or let "target" callback always return an error with
>   a dev_err message that you don't accept frequency changes
>   from userspace.

Thanks for the input. Will implement something similar to
what you suggested for the next re-spin.

-Sibi

> 
> Cheers,
> MyungJoo.