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Date: Fri, 12 Jan 2024 16:32:45 +0000
From: Andre Przywara <andre.przywara@arm.com>
To: Alexey Klimov <alexey.klimov@linaro.org>
Cc: anarsoul@gmail.com, tiny.windzz@gmail.com, linux-sunxi@lists.linux.dev,
 rafael@kernel.org, devicetree@vger.kernel.org,
 linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
 wens@csie.org, jernej.skrabec@gmail.com, samuel@sholland.org,
 daniel.lezcano@linaro.org, peter.griffin@linaro.org, klimov.linux@gmail.com
Subject: Re: [PATCH RESEND] arm64: dts: allwinner: a64: Add thermal trip
 points for GPU
Message-ID: <20240112163245.3be1aeaa@donnerap.manchester.arm.com>
In-Reply-To: <20240101000008.65747-1-alexey.klimov@linaro.org>
References: <20240101000008.65747-1-alexey.klimov@linaro.org>
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On Mon,  1 Jan 2024 00:00:08 +0000
Alexey Klimov <alexey.klimov@linaro.org> wrote:

Hi Alexey,

> Without trip points for GPU, the following errors are printed in the
> dmesg log and the sun8i-thermal driver fails to load:
> 
> thermal_sys: Failed to find 'trips' node
> thermal_sys: Failed to find trip points for thermal-sensor id=1
> sun8i-thermal: probe of 1c25000.thermal-sensor failed with error -22

Regardless of whether we should really *require* trip points (what Icenowy
wanted to fix), I think it's good to have those values in the DT.

The only question I have: where do those values come from? Is this coming
from some BSP, or some downstream repository? If there are multiple
sources: are the values across them consistent?
I have seen a lot careless and unreflecting copy&paste in the past, so
just want to make sure we get the right values.

Cheers,
Andre

> When thermal zones are defined, trip points definitions are mandatory.
> Trip values for the GPU are assumed to be the same values as the CPU
> ones. The available specs do not provide any hints about thermal regimes
> for the GPU and it seems GPU is implemented on the same die as the CPU.
> 
> Tested on Pine a64+.
> 
> Cc: Samuel Holland <samuel@sholland.org>
> Cc: Jernej Skrabec <jernej.skrabec@gmail.com>
> Cc: Chen-Yu Tsai <wens@csie.org>
> Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
> Cc: devicetree@vger.kernel.org
> Signed-off-by: Alexey Klimov <alexey.klimov@linaro.org>
> ---
>  arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi | 46 +++++++++++++++++++
>  1 file changed, 46 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi b/arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi
> index 62f45f71ec65..07963eea1bf0 100644
> --- a/arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi
> +++ b/arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi
> @@ -243,6 +243,29 @@ gpu0_thermal: gpu0-thermal {
>  			polling-delay-passive = <0>;
>  			polling-delay = <0>;
>  			thermal-sensors = <&ths 1>;
> +
> +			trips {
> +				gpu0_alert0: gpu0_alert0 {
> +					/* milliCelsius */
> +					temperature = <75000>;
> +					hysteresis = <2000>;
> +					type = "passive";
> +				};
> +
> +				gpu0_alert1: gpu0_alert1 {
> +					/* milliCelsius */
> +					temperature = <90000>;
> +					hysteresis = <2000>;
> +					type = "hot";
> +				};
> +
> +				gpu0_crit: gpu0_crit {
> +					/* milliCelsius */
> +					temperature = <110000>;
> +					hysteresis = <2000>;
> +					type = "critical";
> +				};
> +			};
>  		};
>  
>  		gpu1_thermal: gpu1-thermal {
> @@ -250,6 +273,29 @@ gpu1_thermal: gpu1-thermal {
>  			polling-delay-passive = <0>;
>  			polling-delay = <0>;
>  			thermal-sensors = <&ths 2>;
> +
> +			trips {
> +				gpu1_alert0: gpu1_alert0 {
> +					/* milliCelsius */
> +					temperature = <75000>;
> +					hysteresis = <2000>;
> +					type = "passive";
> +				};
> +
> +				gpu1_alert1: gpu1_alert1 {
> +					/* milliCelsius */
> +					temperature = <90000>;
> +					hysteresis = <2000>;
> +					type = "hot";
> +				};
> +
> +				gpu1_crit: gpu1_crit {
> +					/* milliCelsius */
> +					temperature = <110000>;
> +					hysteresis = <2000>;
> +					type = "critical";
> +				};
> +			};
>  		};
>  	};
>