Re: [PATCH 2/2] arm64: dts: freescale: add i.MX91 9x9 QSB basic support

[Andrew Lunn]

On Fri, Mar 20, 2026 at 02:18:31PM +0800, Peng Fan wrote:
> On Thu, Mar 19, 2026 at 04:43:40PM +0100, Andrew Lunn wrote:
> >> +&eqos {
> >> +	phy-handle = <&ethphy1>;
> >> +	phy-mode = "rgmii-id";
> >> +	pinctrl-0 = <&pinctrl_eqos>;
> >> +	pinctrl-names = "default";
> >> +	status = "okay";
> >> +
> >> +	mdio {
> >> +		compatible = "snps,dwmac-mdio";
> >> +		#address-cells = <1>;
> >> +		#size-cells = <0>;
> >> +		clock-frequency = <5000000>;
> >
> >Is that a valid property for "snps,dwmac-mdio"?
> 
> It is a valid property in 
> Documentation/devicetree/bindings/net/mdio.yaml

Yes, it is in general a valid property. But does snps,dwmac-mdio
actually implement it?

The danger here is, it is currently ignored, and the MDIO bus is
clocked at 2.5MHz, and your board works. But sometime in the future,
somebody actually implements it, your board jumps to 5MHz, and stops
working.

That is not the usual definition of a regression, so i guess we will
leave your board broken.

So you need to accept the risk. Or remove the property. Or actually
implement the property.

   Andrew