Re: [PATCH 2/2] arm64: dts: rockchip: Add EmbedFire LubanCat 4 board

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Contradiction between physical PCB RX delay and RGMII PHY mode setting, risking Gigabit Ethernet instability.
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commit a30ca0bb9560e6ed7ecdf88333f509d579374640
Author: LemonFan-maker <2254650260@qq.com>

arm64: dts: rockchip: Add EmbedFire LubanCat 4 board

This commit adds basic device tree support for the EmbedFire LubanCat 4,
a single board computer based on the Rockchip RK3588S SoC. The enabled
peripherals allow the board to boot via serial, eMMC, or SD card, and
provide networking over Gigabit Ethernet.

> diff --git a/arch/arm64/boot/dts/rockchip/rk3588s-lubancat-4.dts b/arch/arm64/boot/dts/rockchip/rk3588s-lubancat-4.dts
> new file mode 100644
> index 0000000000000..f8c78df4a14ba
> --- /dev/null
> +++ b/arch/arm64/boot/dts/rockchip/rk3588s-lubancat-4.dts

[ ... ]

> +&gmac1 {
> +	clock_in_out = "output";
> +	phy-handle = <&rgmii_phy1>;
> +	/* The board has 1.5ns delays on RX lines; TX delay is provided by the MAC. */
> +	phy-mode = "rgmii-rxid";

[Severity: Medium]
Is this phy-mode setting correct given the board's physical delay?

The comment states the board already provides 1.5ns of physical delay on the
RX lines. However, setting phy-mode to "rgmii-rxid" explicitly instructs the
PHY to add its own internal RX delay (typically ~2.0ns).

A total RX delay of ~3.5ns within a 4ns RGMII data window might shift the
clock edge out of the safe sampling region, which can cause packet loss
or link failure at Gigabit speeds.

Could you clarify if the comment about the board is outdated, or if a
different phy-mode (like "rgmii" or "rgmii-txid") was intended here?

> +	pinctrl-0 = <&gmac1_miim
> +		     &gmac1_tx_bus2
> +		     &gmac1_rx_bus2
> +		     &gmac1_rgmii_clk
> +		     &gmac1_rgmii_bus>;
> +	pinctrl-names = "default";
> +	tx_delay = <0x1b>;
> +	status = "okay";
> +};

[ ... ]

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Sashiko AI review · https://sashiko.dev/#/patchset/20260705135014.1004166-1-2254650260@qq.com?part=2