linux-kernel - Re: [PATCH v2] arm64: dts: allwinner: a64: Add GPU thermal trips to the SoC dtsi

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Message-Id: <20240904004615.15ccf4ec1d764c5a163ebc13@arnet.am>
Date: Wed, 4 Sep 2024 00:46:15 +0400
From: նորայր <norayr@...et.am>
To: Dragan Simic <dsimic@...jaro.org>
Cc: linux-sunxi@...ts.linux.dev, 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, uwu@...nowy.me,
 wenst@...omium.org, broonie@...nel.org, daniel.lezcano@...aro.org
Subject: Re: [PATCH v2] arm64: dts: allwinner: a64: Add GPU thermal trips to
 the SoC dtsi

Hello,

I have tested this patch to the device tree on my pinephone (1.2 edition) under Gentoo Linux (vanilla-sources-6.10.7)
before the test, my dmesg contained:

---
[    0.156933] thermal_sys: Registered thermal governor 'fair_share'
[    0.156942] thermal_sys: Registered thermal governor 'bang_bang'
[    0.156960] thermal_sys: Registered thermal governor 'step_wise'
[    0.156976] thermal_sys: Registered thermal governor 'user_space'
[    0.156992] thermal_sys: Registered thermal governor 'power_allocator'
[    1.409536] thermal_sys: Failed to find 'trips' node
[    1.409555] thermal_sys: Failed to find trip points for thermal-sensor id=1
[    1.409594] thermal_sys: Failed to find 'trips' node
[    1.409607] thermal_sys: Failed to find trip points for thermal-sensor id=2
----

after applying the patch and booting with newer dtb, when i grep for the string 'thermal' in dmesg i only have:

----
[    0.159456] thermal_sys: Registered thermal governor 'fair_share'
[    0.159465] thermal_sys: Registered thermal governor 'bang_bang'
[    0.159484] thermal_sys: Registered thermal governor 'step_wise'
[    0.159499] thermal_sys: Registered thermal governor 'user_space'
[    0.159515] thermal_sys: Registered thermal governor 'power_allocator'
----

Tested-by: Norayr Chilingarian <norayr@...et.am>

On Tue, 20 Aug 2024 05:57:47 +0200
Dragan Simic <dsimic@...jaro.org> wrote:

> 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.
> 
> Signed-off-by: Dragan Simic <dsimic@...jaro.org>
> ---
> 
> Notes:
>     Changes in v2:
>       - Added "a64:" at the end of the patch subject prefix and adjusted the
>         patch subject a bit, to match the usual prefix better
>       - Dropped the removal of potentially redundant comments that describe
>         the units, as suggested by Icenowy [1] and Chen-Yu [2]
>     
>     Link to v1: https://lore.kernel.org/linux-sunxi/a17e0df64c5b976b47f19c5a29c02759cd9e5b8c.1723427375.git.dsimic@manjaro.org/T/#u
>     
>     [1] https://lore.kernel.org/linux-sunxi/24406e36f6facd93e798113303e22925b0a2dcc1.camel@icenowy.me/
>     [2] https://lore.kernel.org/linux-sunxi/662f2332efb1d6c21e722066562a72b9@manjaro.org/T/#mdd7b18962c1ae339141061af51b89cd68bc04d50
> 
>  arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi b/arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi
> index e868ca5ae753..a5c3920e0f04 100644
> --- a/arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi
> +++ b/arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi
> @@ -263,13 +263,29 @@ gpu0_thermal: gpu0-thermal {
>  			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";
> +				};
> +			};
>  		};
>  	};
>  



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