linux-kernel - Re: [PATCH] arm64: dts: allwinner: Add GPU thermal trips to the SoC dtsi for A64

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Message-ID: <24406e36f6facd93e798113303e22925b0a2dcc1.camel@icenowy.me>
Date: Mon, 12 Aug 2024 10:40:36 +0800
From: Icenowy Zheng <uwu@...nowy.me>
To: Dragan Simic <dsimic@...jaro.org>, linux-sunxi@...ts.linux.dev
Cc: wens@...e.org, jernej.skrabec@...il.com, samuel@...lland.org, 
	linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org, 
	robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org, 
	linux-kernel@...r.kernel.org, wenst@...omium.org, broonie@...nel.org
Subject: Re: [PATCH] arm64: dts: allwinner: Add GPU thermal trips to the SoC
 dtsi for A64

在 2024-08-12星期一的 04:00 +0200，Dragan Simic写道：
> Add thermal trips for the two GPU thermal sensors found in the
> Allwinner A64.
> There's only one GPU OPP defined since the commit 1428f0c19f9c
> ("arm64: dts:
> allwinner: a64: Run GPU at 432 MHz"), so defining only the critical
> thermal
> trips makes sense for the A64's two GPU thermal zones.
> 
> Having these critical thermal trips defined ensures that no hot spots
> develop
> inside the SoC die that exceed the maximum junction temperature. 
> That might
> have been possible before, although quite unlikely, because the CPU
> and GPU
> portions of the SoC are packed closely inside the SoC, so the
> overheating GPU
> would inevitably result in the heat soaking into the CPU portion of
> the SoC,
> causing the CPU thermal sensor to return high readings and trigger
> the CPU
> critical thermal trips.  However, it's better not to rely on the heat
> soak
> and have the critical GPU thermal trips properly defined instead.
> 
> While there, remove a few spotted comments that are rather redundant,
> because
> it's pretty much obvious what units are used in those places.

This should be another individual patch, I think.

> 
> Signed-off-by: Dragan Simic <dsimic@...jaro.org>
> ---
>  arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi | 22 ++++++++++++++---
> --
>  1 file changed, 16 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi
> b/arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi
> index e868ca5ae753..bc5d3a2e6c98 100644
> --- a/arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi
> +++ b/arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi
> @@ -212,7 +212,6 @@ timer {
>  
>         thermal-zones {
>                 cpu_thermal: cpu0-thermal {
> -                       /* milliseconds */

The unit of a 0 isn't not so obvious I think, so I suggest to keep
this.

>                         polling-delay-passive = <0>;
>                         polling-delay = <0>;
>                         thermal-sensors = <&ths 0>;
> @@ -236,40 +235,51 @@ map1 {
>  
>                         trips {
>                                 cpu_alert0: cpu-alert0 {
> -                                       /* milliCelsius */
>                                         temperature = <75000>;
>                                         hysteresis = <2000>;
>                                         type = "passive";
>                                 };
>  
>                                 cpu_alert1: cpu-alert1 {
> -                                       /* milliCelsius */
>                                         temperature = <90000>;
>                                         hysteresis = <2000>;
>                                         type = "hot";
>                                 };
>  
>                                 cpu_crit: cpu-crit {
> -                                       /* milliCelsius */
>                                         temperature = <110000>;
>                                         hysteresis = <2000>;
>                                         type = "critical";
>                                 };
>                         };
>                 };
>  
>                 gpu0_thermal: gpu0-thermal {
> -                       /* milliseconds */
>                         polling-delay-passive = <0>;
>                         polling-delay = <0>;
>                         thermal-sensors = <&ths 1>;
> +
> +                       trips {
> +                               gpu0_crit: gpu0-crit {
> +                                       temperature = <110000>;
> +                                       hysteresis = <2000>;
> +                                       type = "critical";
> +                               };
> +                       };
>                 };
>  
>                 gpu1_thermal: gpu1-thermal {
> -                       /* milliseconds */
>                         polling-delay-passive = <0>;
>                         polling-delay = <0>;
>                         thermal-sensors = <&ths 2>;
> +
> +                       trips {
> +                               gpu1_crit: gpu1-crit {
> +                                       temperature = <110000>;
> +                                       hysteresis = <2000>;
> +                                       type = "critical";
> +                               };
> +                       };
>                 };
>         };
>