linux-kernel - Re: [PATCH v3 4/5] cpufreq: apple-soc: Add new driver to control Apple SoC CPU P-states

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Message-ID: <8c7b25f0-aee2-c3ee-c6da-3432b6513c57@marcan.st>
Date:   Mon, 14 Nov 2022 20:06:50 +0900
From:   Hector Martin <marcan@...can.st>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Sven Peter <sven@...npeter.dev>,
        Alyssa Rosenzweig <alyssa@...enzweig.io>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Marc Zyngier <maz@...nel.org>,
        Mark Kettenis <mark.kettenis@...all.nl>, asahi@...ts.linux.dev,
        linux-arm-kernel@...ts.infradead.org, linux-pm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 4/5] cpufreq: apple-soc: Add new driver to control
 Apple SoC CPU P-states

For the benefit of everyone else: I screwed up a reply from mobile and
ended up with a brief exchange offline, but here's the useful part of
the context. Viresh also pointed out dropping opp-shared if we don't use
that mechanism, so I'll do that for v4.

On 14/11/2022 16.03, Viresh Kumar wrote:
> On 14-11-22, 15:57, Hector Martin wrote:
>> There is no way to express this relationship with OPP tables without
>> duplicating the tables themselves.
> 
> Can you show how the DT looks in this case ? I am still not clear on what the
> scenario is here :(

Here's the most complicated one we have so far: 20 cores and 6 clusters
sharing 2 OPP tables (mind the include and define fun - this is the best
way we could come up with to express two SoC dies glued together into
one MCM).

https://github.com/AsahiLinux/linux/blob/asahi-wip/arch/arm64/boot/dts/apple/t6002.dtsi

- Hector