Re: [PATCH 4/5] arm64: dts: imx91-11x11-evk: add reset gpios for ethernet PHYs

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Missing `compatible` string with PHY ID in ethernet-phy nodes causes silent probe failure when using reset-gpios.
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commit 3c4c46607dcfd2582ce8a02581310d0901a9d667
Author: Joy Zou <joy.zou@nxp.com>

arm64: dts: imx91-11x11-evk: add reset gpios for ethernet PHYs

This commit adds reset GPIO properties for the ethernet PHYs using
an I2C GPIO expander. This allows the PHYs on both the EQOS and FEC
interfaces to be reset during initialization.

> diff --git a/arch/arm64/boot/dts/freescale/imx91-11x11-evk.dts b/arch/arm64/boot/dts/freescale/imx91-11x11-evk.dts
> --- a/arch/arm64/boot/dts/freescale/imx91-11x11-evk.dts
> +++ b/arch/arm64/boot/dts/freescale/imx91-11x11-evk.dts
[ ... ]
> @@ -198,6 +198,9 @@ mdio {
>  
>  		ethphy1: ethernet-phy@1 {
>  			reg = <1>;
> +			reset-gpios = <&pcal6524 15 GPIO_ACTIVE_LOW>;

Will this cause a silent probe failure if the PHY is held in reset at boot?

Because there is no explicit compatible string with the PHY ID (for example,
compatible = "ethernet-phy-idXXXX.YYYY"), the MDIO core must auto-detect
the PHY by reading its ID registers over the MDIO bus.

If the PHY is currently held in reset, the MDIO read will fail and return
0xFFFF. This causes get_phy_device() to return -ENODEV before the device
is created.

Since the device instantiation is skipped, the reset-gpios are never requested
or deasserted, and the I2C expander probe deferral mechanism is bypassed,
leaving the ethernet interface permanently disabled.

Should these PHY nodes explicitly include the PHY ID in the compatible property
to bypass the hardware ID read, allowing the kernel to wait for the I2C
expander to be ready and properly deassert the reset?

> +			reset-assert-us = <10000>;
> +			reset-deassert-us = <80000>;
>  			realtek,clkout-disable;
>  		};
>  	};

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Sashiko AI review · https://sashiko.dev/#/patchset/20260519-b4-imx91-qsb-opt-v1-0-9b416d2dc224@nxp.com?part=4