Re: [PATCH 3/3] arm64: dts: exynos7870-j6lte: add Sharp GP2AP070S proximity sensor

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The device tree explicitly configures the pins for a bit-banged `i2c-gpio` bus to an alternate hardware function (`EXYNOS_PIN_FUNC_3`), which contradicts the use of the GPIO controller.
--

--- Patch [3]: [PATCH 3/3] arm64: dts: exynos7870-j6lte: add Sharp GP2AP070S proximity sensor ---
commit 930975d14f401bcd9e271c568ee73bd61323dc94
Author: Kaustabh Chakraborty <kauschluss@disroot.org>

arm64: dts: exynos7870-j6lte: add Sharp GP2AP070S proximity sensor

This commit adds a devicetree node for the Sharp GP2AP070S proximity sensor
on the Exynos7870 j6lte platform. It sets up an i2c-gpio bus for the sensor
and configures a dedicated fixed regulator for the sensor's VDD supply.

> diff --git a/arch/arm64/boot/dts/exynos/exynos7870-j6lte.dts b/arch/arm64/boot/dts/exynos/exynos7870-j6lte.dts
> index de30d0970336f..dd493138fed6e 100644
> --- a/arch/arm64/boot/dts/exynos/exynos7870-j6lte.dts
> +++ b/arch/arm64/boot/dts/exynos/exynos7870-j6lte.dts

[ ... ]

> @@ -579,6 +624,12 @@ bt_enable: bt-enable-pins {
>  		samsung,pin-pud = <EXYNOS_PIN_PULL_DOWN>;
>  	};
>  
> +	i2c_proxm_bus: i2c-proxm-bus-pins {
> +		samsung,pins = "gpf4-3", "gpf4-2";
> +		samsung,pin-function = <EXYNOS_PIN_FUNC_3>;

[Severity: Medium]
Does this pin configuration conflict with the i2c-gpio usage?

This node configures the pins to an alternate hardware function
(EXYNOS_PIN_FUNC_3) rather than GPIO, but it is referenced by the
bit-banged i2c-proximity node.

When the i2c-proximity device is instantiated, the pinctrl core applies
this state. Shortly after, the i2c-gpio driver probes and requests the pins
via gpiod_get(), which causes the pinctrl driver to silently overwrite the
pin function back to GPIO input/output.

While the driver ultimately recovers the pins for GPIO usage, configuring
them to an alternate hardware function initially creates a window where the
pins might be driven by an uninitialized hardware IP block. This risks
causing spurious signals or electrical contention on the I2C bus during
boot.

> +		samsung,pin-pud = <EXYNOS_PIN_PULL_NONE>;
> +	};
> +
>  	wlan_enable: wlan-enable-pins {
>  		samsung,pins = "gpd3-6";
>  		samsung,pin-function = <EXYNOS_PIN_FUNC_OUTPUT>;

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260723-gp2ap070s-v1-0-b8ca3a4c10dd@disroot.org?part=3