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

From: Lorenzo Bianconi <lorenzo@kernel.org>
To: Andrew Lunn <andrew@lunn.ch>
Cc: netdev@vger.kernel.org, nbd@nbd.name, john@phrozen.org,
	sean.wang@mediatek.com, Mark-MC.Lee@mediatek.com,
	davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
	pabeni@redhat.com, Sam.Shih@mediatek.com,
	linux-mediatek@lists.infradead.org, devicetree@vger.kernel.org,
	robh@kernel.org, landen.chao@mediatek.com
Subject: Re: [PATCH net-next 01/14] arm64: dts: mediatek: mt7986: introduce ethernet nodes
Date: Sat, 14 May 2022 11:49:14 +0200	[thread overview]
Message-ID: <Yn97GqujwYlljkdH@lore-desk> (raw)
In-Reply-To: <YnlFBr1wgb/hlduy@lunn.ch>

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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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