linux-kernel - Re: [PATCH v3] arm64: dts: mediatek: mt8183: disable thermal zones without trips.

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Date:   Tue, 4 Oct 2022 12:47:30 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Amjad Ouled-Ameur <aouledameur@...libre.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Matthias Brugger <matthias.bgg@...il.com>
Cc:     linux-mediatek@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] arm64: dts: mediatek: mt8183: disable thermal zones
 without trips.


Hi Amjad,

On 04/10/2022 12:11, Amjad Ouled-Ameur wrote:
> Thermal zones without trip point are not registered by thermal core.
> 
> tzts1 ~ tzts6 zones of mt8183 were intially introduced for test-purpose
> only.
> 
> Disable the zones above and keep only cpu_thermal enabled.

It does not make sense to disable the thermal zones. Either the thermal 
zones are needed or they are not. Keeping them for debug purpose is not 
desired.

Alternatively to removal, you can:

  - remove 'sustainable-power'
  - add a passive trip point, optionally a hot trip point and a critical 
trip point

The passive trip point will allow the userspace to set a value in order 
to get notified about the devices temperature (writable trip point). 
The hot temperature will send a notification to userspace so it can take 
a last chance decision to drop the temperature before the critical 
temperature.

The passive trip point temperature could be a high temperature.

The mitigation is also managed from userspace as a whole.


> Signed-off-by: Amjad Ouled-Ameur <aouledameur@...libre.com>
> ---
>   arch/arm64/boot/dts/mediatek/mt8183.dtsi | 6 ++++++
>   1 file changed, 6 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/mediatek/mt8183.dtsi b/arch/arm64/boot/dts/mediatek/mt8183.dtsi
> index 9d32871973a2..53f7a0fbaa88 100644
> --- a/arch/arm64/boot/dts/mediatek/mt8183.dtsi
> +++ b/arch/arm64/boot/dts/mediatek/mt8183.dtsi
> @@ -1191,6 +1191,7 @@ tzts1: tzts1 {
>   				polling-delay = <0>;
>   				thermal-sensors = <&thermal 1>;
>   				sustainable-power = <5000>;
> +				status = "disabled";
>   				trips {};
>   				cooling-maps {};
>   			};
> @@ -1200,6 +1201,7 @@ tzts2: tzts2 {
>   				polling-delay = <0>;
>   				thermal-sensors = <&thermal 2>;
>   				sustainable-power = <5000>;
> +				status = "disabled";
>   				trips {};
>   				cooling-maps {};
>   			};
> @@ -1209,6 +1211,7 @@ tzts3: tzts3 {
>   				polling-delay = <0>;
>   				thermal-sensors = <&thermal 3>;
>   				sustainable-power = <5000>;
> +				status = "disabled";
>   				trips {};
>   				cooling-maps {};
>   			};
> @@ -1218,6 +1221,7 @@ tzts4: tzts4 {
>   				polling-delay = <0>;
>   				thermal-sensors = <&thermal 4>;
>   				sustainable-power = <5000>;
> +				status = "disabled";
>   				trips {};
>   				cooling-maps {};
>   			};
> @@ -1227,6 +1231,7 @@ tzts5: tzts5 {
>   				polling-delay = <0>;
>   				thermal-sensors = <&thermal 5>;
>   				sustainable-power = <5000>;
> +				status = "disabled";
>   				trips {};
>   				cooling-maps {};
>   			};
> @@ -1236,6 +1241,7 @@ tztsABB: tztsABB {
>   				polling-delay = <0>;
>   				thermal-sensors = <&thermal 6>;
>   				sustainable-power = <5000>;
> +				status = "disabled";
>   				trips {};
>   				cooling-maps {};
>   			};


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