linux-kernel - Re: [RFC V7 2/2] OPP: Allow "opp-hz" and "opp-microvolt" to contain magic values

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Message-ID: <CAPDyKFrBsb_gKQpPkSTNpSjqYGir9nXKzSE09qkyU=zr_S-5xA@mail.gmail.com>
Date:   Tue, 28 Nov 2017 17:14:57 +0100
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     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" <linux-pm@...r.kernel.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        Sudeep Holla <sudeep.holla@....com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC V7 2/2] OPP: Allow "opp-hz" and "opp-microvolt" to contain
 magic values

On 31 October 2017 at 13:47, Viresh Kumar <viresh.kumar@...aro.org> wrote:
> On some platforms the exact frequency or voltage may be hidden from the
> OS by the firmware. Allow such configurations to pass magic values in
> the "opp-hz" or the "opp-microvolt" properties, which should be
> interpreted in a platform dependent way.
>
> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>

This seems like a reasonable extension to me!

Reviewed-by: Ulf Hansson <ulf.hansson@...aro.org>

Kind regards
Uffe

> ---
>  Documentation/devicetree/bindings/opp/opp.txt | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/opp/opp.txt b/Documentation/devicetree/bindings/opp/opp.txt
> index 203e09fe7698..9c5056fb120f 100644
> --- a/Documentation/devicetree/bindings/opp/opp.txt
> +++ b/Documentation/devicetree/bindings/opp/opp.txt
> @@ -166,6 +166,12 @@ properties.
>    "power-domains" property. Also, either all or none of the OPP nodes in an OPP
>    table should have it set.
>
> +
> +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.
> +
>  Example 1: Single cluster Dual-core ARM cortex A9, switch DVFS states together.
>
>  / {
> --
> 2.15.0.rc1.236.g92ea95045093
>