linux-kernel - Re: [PATCH v1 7/7] arm64: dts: sdm845: wireup the thermal trip points to cpufreq

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Message-ID: <CAP245DWMz0UfRdD9HHaRF0fvTgYroxLrj5LcTgQMA9DuBm4T8A@mail.gmail.com>
Date:   Mon, 14 Jan 2019 13:52:34 +0530
From:   Amit Kucheria <amit.kucheria@...aro.org>
To:     Matthias Kaehlcke <mka@...omium.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Eduardo Valentin <edubezval@...il.com>,
        Andy Gross <andy.gross@...aro.org>,
        Taniya Das <tdas@...eaurora.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Douglas Anderson <dianders@...omium.org>,
        David Brown <david.brown@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>
Subject: Re: [PATCH v1 7/7] arm64: dts: sdm845: wireup the thermal trip points
 to cpufreq

On Sat, Jan 12, 2019 at 2:06 AM Matthias Kaehlcke <mka@...omium.org> wrote:
>
> Another concern about adding trip points later could be the node
> name. We currently have:
>
>
> trips {
>   cpu0_alert0: trip0 {
>     ...
>   };
>
>   cpu0_crit: trip1 {
>     ...
>   };
> };
>
> If we keep increasing enumeration with the node name this would become:
>
> trips {
>   cpu0_alert0: trip0 {
>     ...
>   };
>
>   cpu0_alert1: trip1 {
>     ...
>   };
>
>   cpu0_crit: trip2 {
>     ...
>   };
> };
>
> i.e. the node name of the critical trip-point changes, which might be
> a concern for dtsi's that override a value, though they should
> probably use the phandle &cpu0_crit anyway. If this is a concern we
> could change the node names to 'alert0' and 'crit'.
>
> I looked around a bit and actually I kinda like the naming scheme used
> by hisilicon/hi6220.dtsi, mediatek/mt8173.dtsi and rockchip/rk3328.dtsi
> (with minor variations):
>
> trips {
>         threshold: trip-point@0 {
>                 temperature = <68000>;
>                 hysteresis = <2000>;
>                 type = "passive";
>         };
>
>         target: trip-point@1 {
>                 temperature = <85000>;
>                 hysteresis = <2000>;
>                 type = "passive";
>         };
>
>         cpu_crit: cpu_crit@0 {
>                 temperature = <115000>;
>                 hysteresis = <2000>;
>                 type = "critical";
>         };
> };
>
> If we were to use this we'd have to adapt it slightly since we have
> multiple thermal zones. In line with the other scheme this could be
> cpuN_threshold, cpuN_target and cpuN_crit.
>

I like this scheme enough that I adopted it for v2.