linux-kernel - Re: [PATCH V3 3/3] arm64: dts: imx8mp: Add thermal zones support

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Date:   Fri, 3 Apr 2020 11:15:53 +0530
From:   Amit Kucheria <amit.kucheria@...durent.com>
To:     Anson Huang <anson.huang@....com>
Cc:     Zhang Rui <rui.zhang@...el.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        Horia Geanta <horia.geanta@....com>,
        Peng Fan <peng.fan@....com>,
        Linux PM list <linux-pm@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        lakml <linux-arm-kernel@...ts.infradead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        dl-linux-imx <linux-imx@....com>
Subject: Re: [PATCH V3 3/3] arm64: dts: imx8mp: Add thermal zones support

On Fri, Apr 3, 2020 at 9:04 AM Anson Huang <anson.huang@....com> wrote:
>
> Hi, Amit
>
> > Subject: Re: [PATCH V3 3/3] arm64: dts: imx8mp: Add thermal zones support
> >
> > On Mon, Mar 23, 2020 at 6:05 PM Anson Huang <Anson.Huang@....com>
> > wrote:
> > >
> > > i.MX8MP has a TMU inside which supports two thermal zones, add support
> > > for them.
> > >
> > > Signed-off-by: Anson Huang <Anson.Huang@....com>
> >
> >
> > [snip]
> >
> > >
> > > +       thermal-zones {
> > > +               cpu-thermal {
> > > +                       polling-delay-passive = <250>;
> > > +                       polling-delay = <2000>;
> > > +                       thermal-sensors = <&tmu 0x0>;
> >
> > No need for 0x0, just use 0
>
> OK.
>
> >
> > > +                       trips {
> > > +                               cpu_alert0: trip0 {
> > > +                                       temperature = <85000>;
> > > +                                       hysteresis = <2000>;
> > > +                                       type = "passive";
> > > +                               };
> > > +
> > > +                               cpu_crit0: trip1 {
> > > +                                       temperature = <95000>;
> > > +                                       hysteresis = <2000>;
> > > +                                       type = "critical";
> > > +                               };
> > > +                       };
> > > +
> > > +                       cooling-maps {
> > > +                               map0 {
> > > +                                       trip = <&cpu_alert0>;
> > > +                                       cooling-device =
> > > +                                               <&A53_0
> > THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
> > > +                                               <&A53_1
> > THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
> > > +                                               <&A53_2
> > THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
> > > +                                               <&A53_3
> > THERMAL_NO_LIMIT THERMAL_NO_LIMIT>;
> > > +                               };
> > > +                       };
> > > +               };
> > > +
> > > +               soc-thermal {
> > > +                       polling-delay-passive = <250>;
> > > +                       polling-delay = <2000>;
> > > +                       thermal-sensors = <&tmu 0x1>;
> >
> > No need for 0x1, just use 1
>
> OK.
>
> >
> > > +                       trips {
> > > +                               soc_alert0: trip0 {
> > > +                                       temperature = <85000>;
> > > +                                       hysteresis = <2000>;
> > > +                                       type = "passive";
> > > +                               };
> > > +
> > > +                               soc_crit0: trip1 {
> > > +                                       temperature = <95000>;
> > > +                                       hysteresis = <2000>;
> > > +                                       type = "critical";
> > > +                               };
> > > +                       };
> >
> > You need a cooling-map here since you have a passive trip point.
>
> Currently, there is no cooling map defined for soc thermal zone, the cpufreq cooling
> is mapped to cpu thermal zone already, so do you think it is OK to leave it as no cooling
> map, or it is better to put cpufreq cooling for soc thermal zone as well?
>

If there is no cooling, why do you need a passive trip point? Just
make it a hot trip that will send you a nofication (if .notify
callback registered).

Regards,
Amit