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

[Lorenzo Bianconi <lorenzo@kernel.org>]

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> On Mon, May 09, 2022 at 06:35:42PM +0200, Lorenzo Bianconi wrote:
> > > > +&eth {
> > > > +	status = "okay";
> > > > +
> > > > +	gmac0: mac@0 {
> > > > +		compatible = "mediatek,eth-mac";
> > > > +		reg = <0>;
> > > > +		phy-mode = "2500base-x";
> > > > +
> > > > +		fixed-link {
> > > > +			speed = <2500>;
> > > > +			full-duplex;
> > > > +			pause;
> > > > +		};
> > > > +	};
> > > > +
> > > > +	gmac1: mac@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

adding Landen to the discussion to provide more hw details.
@Landen: any inputs on it?

Regards,
Lorenzo

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