linux-kernel - Re: [PATCH] arm64: dts: freescale: imx8mp-toradex-smarc: add fan cooling levels

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Message-ID: <aEyaNEFl3gD6snOP@lizhi-Precision-Tower-5810>
Date: Fri, 13 Jun 2025 17:37:56 -0400
From: Frank Li <Frank.li@....com>
To: João Paulo Gonçalves <jpaulo.silvagoncalves@...il.com>
Cc: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>, devicetree@...r.kernel.org,
	imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	João Paulo Gonçalves <joao.goncalves@...adex.com>
Subject: Re: [PATCH] arm64: dts: freescale: imx8mp-toradex-smarc: add fan
 cooling levels

On Fri, Jun 13, 2025 at 01:35:04PM -0300, João Paulo Gonçalves wrote:
> From: João Paulo Gonçalves <joao.goncalves@...adex.com>
>
> The fan controller on this board cannot work in automatic mode, and
> requires software control, the reason is that it has no temperature
> sensor connected.

why not use built-in temperature sensor

tmu: tmu@...60000 {
                                compatible = "fsl,imx8mp-tmu";
                                reg = <0x30260000 0x10000>;
                                clocks = <&clk IMX8MP_CLK_TSENSOR_ROOT>;
                                nvmem-cells = <&tmu_calib>;
                                nvmem-cell-names = "calib";
                                #thermal-sensor-cells = <1>;
                        };

Frank

>
> Given that this board is a development kit and does not have any
> specific fan, add a default single cooling level that would enable the
> fan to spin with a 100% duty cycle, enabling a safe default.
>
> Signed-off-by: João Paulo Gonçalves <joao.goncalves@...adex.com>
> ---
>  arch/arm64/boot/dts/freescale/imx8mp-toradex-smarc-dev.dts | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/arch/arm64/boot/dts/freescale/imx8mp-toradex-smarc-dev.dts b/arch/arm64/boot/dts/freescale/imx8mp-toradex-smarc-dev.dts
> index 55b8c5c14fb4f3e7407243760ac01b0aca0dacf5..5f233304cea747d3f04a748265f96696668c9d6b 100644
> --- a/arch/arm64/boot/dts/freescale/imx8mp-toradex-smarc-dev.dts
> +++ b/arch/arm64/boot/dts/freescale/imx8mp-toradex-smarc-dev.dts
> @@ -213,6 +213,7 @@ fan_controller: fan@18 {
>  		#pwm-cells = <2>;
>
>  		fan {
> +			cooling-levels = <255>;
>  			pwms = <&fan_controller 40000 PWM_POLARITY_INVERTED>;
>  		};
>  	};
>
> ---
> base-commit: 1a2ad59da68dd294f994efbf68c5d671f6b42fad
> change-id: 20250613-tdx-smarc-imx8mp-fan-cooling-level-b67265ae2c49
>
> Best regards,
> --
> João Paulo Gonçalves <joao.goncalves@...adex.com>
>