Re: [PATCH 2/2] arm64: dts: qcom: sc8280xp-x13s: Use predefined MCLK pinctrl

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Silent reduction of camera MCLK drive strength from 16 mA to 6 mA.
--

commit 68374459d8e6941a056f52b1b8fa71811fd7137a
Author: Pengyu Luo <mitltlatltl@gmail.com>

arm64: dts: qcom: sc8280xp-x13s: Use predefined MCLK pinctrl

This commit switches the ThinkPad X13s to use the predefined MCLK pinctrl
configuration from the sc8280xp SoC DTSI. It drops the local MCLK pin
definition from the camera pinctrl node.

> diff --git a/arch/arm64/boot/dts/qcom/sc8280xp-lenovo-thinkpad-x13s.dts b/arch/arm64/boot/dts/qcom/sc8280xp-lenovo-thinkpad-x13s.dts
> index d84ca010ab9dc..1e256b16b3e6f 100644
> --- a/arch/arm64/boot/dts/qcom/sc8280xp-lenovo-thinkpad-x13s.dts
> +++ b/arch/arm64/boot/dts/qcom/sc8280xp-lenovo-thinkpad-x13s.dts
> @@ -674,8 +674,9 @@ camera@10 {
>  		reg = <0x10>;
>  
>  		reset-gpios = <&tlmm 15 GPIO_ACTIVE_LOW>;
> +
> +		pinctrl-0 = <&cam_rgb_default>, <&cam_mclk3_default>;
>  		pinctrl-names = "default";
> -		pinctrl-0 = <&cam_rgb_default>;
>  
>  		leds = <&privacy_led>;
>  		led-names = "privacy";

[ ... ]

> @@ -1552,13 +1553,6 @@ cam_indicator_en: cam-indicator-en-state {
>  	};
>  
>  	cam_rgb_default: cam-rgb-default-state {
> -		mclk-pins {
> -			pins = "gpio17";
> -			function = "cam_mclk";
> -			drive-strength = <16>;
> -			bias-disable;
> -		};
> -

[Severity: High]
Does this unintentionally reduce the camera MCLK drive strength?

The commit message notes this is dropping a duplicate MCLK pin definition, but
the generic cam_mclk3_default definition in sc8280xp.dtsi now used by the
camera node defaults to a lower drive strength of 6 mA:

arch/arm64/boot/dts/qcom/sc8280xp.dtsi:
	cam_mclk3_default: cam-mclk3-default-state {
		pins = "gpio17";
		function = "cam_mclk";
		drive-strength = <6>;
		bias-disable;
	};

Reducing the drive capability from 16 mA to 6 mA for a high-frequency master
clock signal routed over long traces might degrade signal integrity.

Could this lead to intermittent or complete camera initialization failures on
this hardware?

>  		sc-rgb-xshut-n-pins {
>  			pins = "gpio15";
>  			function = "gpio";

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260607160435.36546-1-mitltlatltl@gmail.com?part=2