Re: [PATCH] arm64: dts: renesas: r8a779g3: Update thermal trip points on V4H Sparrow Hawk

[Marek Vasut <marek.vasut@mailbox.org>]

On 8/6/25 11:35 AM, Geert Uytterhoeven wrote:
> Hi Marek,

Hi,

>> +       #cooling-cells = <2>;
> 
> This is only present for the first CPU core, and map{0,1,3} refer
> only to a76_0, because all four CPU cores are driven by a single clock
> (Z0), right?

That seems correct.

>> +
>> +       a76_0_thermal_idle: thermal-idle {
>> +               #cooling-cells = <2>;
>> +               duration-us = <10000>;
>> +               exit-latency-us = <500>;
>> +       };
>> +};
> 
>> +/* THS sensor in SoC near CA76 cores does more progressive cooling. */
>> +&sensor_thermal_ca76 {
>> +       critical-action = "shutdown";
>> +
>> +       cooling-maps {
>> +               /*
>> +                * The cooling-device minimum and maximum parameters inversely
>> +                * match opp-table-0 {} node entries in r8a779g0.dtsi, in other
>> +                * words, 0 refers to 1.8 GHz OPP and 4 refers to 500 MHz OPP.
>> +                * This is because they refer to cooling levels, where maximum
>> +                * cooling level happens at 500 MHz OPP, when the CPU core is
>> +                * running slowly and therefore generates least heat.
> 
> That applies to cooling-device = <&a76_[0-3] ...>...

Do you want me to add this line into the comment ?

>> +                */
>> +               map0 {
>> +                       /* At 68C, inhibit 1.7 GHz and 1.8 GHz modes */
>> +                       trip = <&sensor3_passive_low>;
>> +                       cooling-device = <&a76_0 2 4>;
>> +                       contribution = <128>;
>> +               };
>> +
>> +               map1 {
>> +                       /* At 72C, inhibit 1.5 GHz mode */
>> +                       trip = <&sensor3_passive_mid>;
>> +                       cooling-device = <&a76_0 3 4>;
>> +                       contribution = <256>;
>> +               };
>> +
>> +               map2 {
>> +                       /* At 76C, start injecting idle states */
>> +                       trip = <&sensor3_passive_hi>;
>> +                       cooling-device = <&a76_0_thermal_idle 0 80>,
>> +                                        <&a76_1_thermal_idle 0 80>,
>> +                                        <&a76_2_thermal_idle 0 80>,
>> +                                        <&a76_3_thermal_idle 0 80>;
> 
> ... but what do "0 80" refer to? I couldn't find in the thermal-idle
> bindings what exactly are the minimum and maximum cooling states here.
The comments in drivers/thermal/cpuidle_cooling.c clarify that, it is 
the idle injection rate in percent, in this case the cooling can inject 
idle states up to 80% of time.

+CC Daniel in case they want to chime in on that.