linux-kernel - Re: [PATCH V8 3/3] OPP: Allow "opp-hz" and "opp-microvolt" to contain magic values

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: <20171227085645.GF8312@vireshk-i7>
Date:   Wed, 27 Dec 2017 14:26:45 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Rob Herring <robh@...nel.org>
Cc:     ulf.hansson@...aro.org, Kevin Hilman <khilman@...nel.org>,
        Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...eaurora.org>,
        Rafael Wysocki <rjw@...ysocki.net>, linux-pm@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        rnayak@...eaurora.org, sudeep.holla@....com,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V8 3/3] OPP: Allow "opp-hz" and "opp-microvolt" to
 contain magic values

On 26-12-17, 14:29, Rob Herring wrote:
> On Mon, Dec 18, 2017 at 03:51:30PM +0530, Viresh Kumar wrote:

> > +On some platforms the exact frequency or voltage may be hidden from the OS by
> > +the firmware and the "opp-hz" or the "opp-microvolt" properties may contain
> > +magic values that represent the frequency or voltage in a firmware dependent
> > +way, for example an index of an array in the firmware.
> 
> I'm still not convinced this is a good idea.

You were kind-of a few days back :)

lkml.kernel.org/r/CAL_JsqK-qtAaM_Ou5NtxcWR3F_q=8rMPJUm-VqGtKhbtWe5SAQ@...l.gmail.com

So here is the deal:

- I proposed "domain-performance-state" property for this stuff
  initially.
- But Kevin didn't like that and proposed reusing "opp-hz" and
  "opp-microvolt", which we all agreed to multiple times..
- And we are back to the same discussion now and its painful and time
  killing for all of us.

TBH, I don't have too strong preferences about any of the suggestions
you guys have and I need you guys to tell me what binding changes to
do here and I will do that.

> If you have firmware 
> partially managing things, then I think we should have platform specific 
> bindings or drivers. 

What about the initial idea then, like "performance-state" for the
power domains ? All platforms will anyway replicate that binding only.

> This is complex enough I'm not taking silence from Stephen as an okay.

Sure, but I am not sure how to make him speak :)

-- 
viresh