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

[Pufan Jin <2254650260@qq.com>]

On Sun, Jul 05, 2026 at 05:11:58PM +0200, Andrew Lunn wrote:
> > +	/* The board has 1.5ns delays on RX lines; TX delay is provided by the MAC. */
>
> That is pretty unusual. How is this RX delay done?

You're right to question this, and I apologise -- the comment was
inaccurate. I re-checked the board schematic and both TXC and RXC
have ~2ns of trace delay added on the PCB (annotated as
"TXC / RXC : delays 2ns" next to the RGMII bus). So neither the MAC
nor the PHY should add any internal delay.

> Ideally, you want to the PHY adding the delay, not the MAC. 99% of
> rockchip boards get this wrong, they have phy-mode 'rgmii', and
> {tx|rx}_delay properties. And i tell developers to swap to 'rgmii-id'
> and remove the delay properties.
>
> With the PCB adding some delays, you board is slightly
> different. Please drop the tx_delay and adjust the phy-mode so the PHY
> adds the delay.

Since the PCB already provides the required clock skew on both
directions, for v2 I will switch to:

    phy-mode = "rgmii";

and drop both the tx_delay property and the misleading comment.

I also need to correct the cover letter: the PHY on the shipping
board revision (20241026) is a Realtek RTL8211F, not a JLSemi JL21xx.
An earlier revision (20240221) used JL21xx, but the current hardware
uses RTL8211F. The cover letter and binding commit message will be
updated accordingly in v2.

I will collect the remaining reviewer feedback before sending v2 and
will re-test the link on hardware with the corrected phy-mode before
posting.

Thanks for the pointer to ethernet-controller.yaml.

Pufan Jin