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From:   Ulf Hansson <ulf.hansson@linaro.org>
Date:   Fri, 21 Jul 2023 13:42:43 +0200
Message-ID: <CAPDyKFpjMWOAbV+b2DcxDWqvRDQCbSC6Ti+KGGPWJoC4Ghp7=w@mail.gmail.com>
Subject: Re: [PATCH v2 08/11] dt-bindings: firmware: arm,scmi: Extend bindings
 for protocol@13
To:     Sudeep Holla <sudeep.holla@arm.com>
Cc:     Cristian Marussi <cristian.marussi@arm.com>,
        Viresh Kumar <vireshk@kernel.org>, Nishanth Menon <nm@ti.com>,
        Stephen Boyd <sboyd@kernel.org>,
        Nikunj Kela <nkela@quicinc.com>,
        Prasad Sodagudi <psodagud@quicinc.com>,
        Alexandre Torgue <alexandre.torgue@foss.st.com>,
        linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org, Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>, devicetree@vger.kernel.org
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On Wed, 19 Jul 2023 at 17:17, Sudeep Holla <sudeep.holla@arm.com> wrote:
>
> On Thu, Jul 13, 2023 at 04:17:35PM +0200, Ulf Hansson wrote:
> > The protocol@13 node is describing the performance scaling option for the
> > ARM SCMI interface, as a clock provider. This is unnecessary limiting, as
> > performance scaling is in many cases not limited to switching a clock's
> > frequency.
> >
> > Therefore, let's extend the binding so the interface can be modelled as a
> > generic performance domaintoo. The common way to describe this, is to use
> > the "power-domain" DT bindings, so let's use that.
> >
>
> One thing I forgot to ask earlier is how we can manage different domain IDs
> for perf and power domains which is the case with current SCMI platforms as
> the spec never mandated or can ever mandate the perf and power domains IDs
> to match. They need not be same anyways.

Based upon what you describe above, I have modelled the perf-domain
and the power-domain as two separate power-domain providers.

A consumer device being hooked up to both domains, would specify the
domain IDs in the second power-domain-cell, along the lines of the
below. Then we would use power-domain-names to specify what each
power-domain represents.

power-domains = <&scmi_pd 2>, <&scmi_dvfs 4>;
power-domain-names = "power", "perf";

I hope this makes it clearer!?

Kind regards
Uffe