linux-kernel - Re: [RFC PATCH 3/9] dt-bindings: clock: Add apple,cluster-clk binding

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Message-ID: <20211012093529.pzzfo44ikq5oc6cl@vireshk-i7>
Date:   Tue, 12 Oct 2021 15:05:29 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
Cc:     Hector Martin <marcan@...can.st>,
        linux-arm-kernel@...ts.infradead.org,
        Alyssa Rosenzweig <alyssa@...enzweig.io>,
        Sven Peter <sven@...npeter.dev>, Marc Zyngier <maz@...nel.org>,
        Mark Kettenis <mark.kettenis@...all.nl>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Catalin Marinas <catalin.marinas@....com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Kevin Hilman <khilman@...nel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 3/9] dt-bindings: clock: Add apple,cluster-clk binding

Apart from what Krzysztof already said:

On 12-10-21, 10:51, Krzysztof Kozlowski wrote:
> On 11/10/2021 18:57, Hector Martin wrote:
> > +    pcluster_opp: opp-table-1 {
> > +        compatible = "operating-points-v2";
> > +        opp-shared;
> > +
> > +        opp01 {
> > +            opp-hz = /bits/ 64 <600000000>;
> > +            opp-microvolt = <781000>;
> > +            opp-level = <1>;

The opp-level thing wasn't designed to work this way, though it may
work just fine. It was designed as a unique key for power-domains,
which don't have opp-hz. The OPP core currently looks at 3 different
values, which can act as a unique key to identify the OPP. clk-rate,
bandwidth and level.

I think this is the first platform which has both hz and level in the
CPUs OPP table. What exactly is level in this case ?

Again, it may work fine, I just don't know where it may end up
breaking :)

-- 
viresh