Re: [PATCH 1/4] ARM: dts: imx6qdl-sabrelite: add mdio phy address 0

[Andrew Lunn]

On Mon, May 11, 2026 at 05:04:56PM -0400, Frank Li wrote:
> According to IEEE 802.3 Clause 22.2.4.5.5 PHYAD (PHY Address), A PHY that
> is connected to the station management entity via the mechanical interface
> defined in 22.6 shall always respond to transactions addressed to PHY
> Address zero <00000>.

Did you read 22.6? I've not seen a mechanical interface as defined in
22.6 for at least 20 years, maybe 30 years.

That cause does not apply in this context.

> -		ethphy: ethernet-phy {
> +		ethphy: ethernet-phy@0 {
>  			compatible = "ethernet-phy-ieee802.3-c22";
> +			reg = <0>;

This could very well break this board. Without a reg value, the core
will find the first PHY on the bus, at whatever address it is at. If
you hard code 0, the PHY must be at 0, otherwise it will not be found.

	Andrew