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

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Date:   Wed, 27 Dec 2017 10:15:26 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Rob Herring <robh+dt@...nel.org>
Cc:     Stephen Boyd <sboyd@...eaurora.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Kevin Hilman <khilman@...nel.org>,
        Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Rafael Wysocki <rjw@...ysocki.net>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        Vincent Guittot <vincent.guittot@...aro.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 26-12-17, 14:23, Rob Herring wrote:
> >         cpu_opp_table: cpu_opp_table {
> >                 compatible = "operating-points-v2";
> >                 opp-shared;
> >
> >                 opp00 {
> >                         opp-hz = /bits/ 64 <208000000>;
> >                         clock-latency-ns = <500000>;
> >                         power-domain-opp = <&domain_opp_1>;
> 
> What is this? opp00 here is not a device. One OPP should not point to
> another. "power-domain-opp" is only supposed to appear in devices
> alongside power-domains properties.

There are two type of devices:

A.) With fixed performance state requirements and they will have the
new "required-opp" property in the device node itself as you said.

B.) Devices which can do DVFS (CPU, MMC, LCD, etc) and those may need
a different performance state of the domain for their individual OPPs
and so we can't have this property in the device all the time.

Does this make sense ?

-- 
viresh