[PATCH net-next 01/14] arm64: dts: mediatek: mt7986: introduce ethernet nodes

[Andrew Lunn]

On Mon, May 09, 2022 at 06:35:42PM +0200, Lorenzo Bianconi wrote:
> > > +&eth {
> > > +	status = "okay";
> > > +
> > > +	gmac0: mac at 0 {
> > > +		compatible = "mediatek,eth-mac";
> > > +		reg = <0>;
> > > +		phy-mode = "2500base-x";
> > > +
> > > +		fixed-link {
> > > +			speed = <2500>;
> > > +			full-duplex;
> > > +			pause;
> > > +		};
> > > +	};
> > > +
> > > +	gmac1: mac at 1 {
> > > +		compatible = "mediatek,eth-mac";
> > > +		reg = <1>;
> > > +		phy-mode = "2500base-x";
> > > +
> > > +		fixed-link {
> > > +			speed = <2500>;
> > > +			full-duplex;
> > > +			pause;
> > > +		};
> > > +	};
> > 
> > Are both connected to the switch? It just seems unusual two have two
> > fixed-link ports.
> 
> afaik mac design supports autoneg only in 10M/100M/1G mode and mt7986 gmac1
> is connected to a 2.5Gbps phy on mt7986-ref board.

The MAC does not normally perform autoneg, the PHY
does. phylib/phylink then tells the MAC the result of the
negotiation. If there is a SERDES/PCS involved, and it is performing
the autoneg, phylink should get told about the result of the autoneg
and it will tell the MAC the result.

So the gmac1 should just have phy-handle pointing to the PHY, not a
fixed link.

      Andrew