linux-kernel - Re: [PATCHv4 1/5] net: dsa: Support internal phy on 'cpu' port

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Date:   Mon, 22 Jan 2018 12:56:44 -0800
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     Sebastian Reichel <sebastian.reichel@...labora.co.uk>,
        Vivien Didelot <vivien.didelot@...oirfairelinux.com>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <kernel@...gutronix.de>,
        Fabio Estevam <fabio.estevam@....com>,
        Ian Ray <ian.ray@...com>, Nandor Han <nandor.han@...com>,
        Rob Herring <robh+dt@...nel.org>,
        "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCHv4 1/5] net: dsa: Support internal phy on 'cpu' port

On 01/22/2018 12:54 PM, Andrew Lunn wrote:
>> Note: there is still technically a misreprentation of how the PHY is
>> "attached" to the network device. In your DTSes, you have to have the
>> CPU port have a "phy-handle" to the internal PHY, while technically it
>> should be the i210 which has a "phy-handle" property to that PHY, and
>> even better, if the e1000e/idb drivers were PHYLIB capable, they could
>> manage it directly.
> 
> Hi Florian
> 
> Err, i don't think i agree. But maybe i'm missunderstanding.
> 
> We have two back-to-back PHYs. I would expect the i210 MAC to have a
> phy-handle pointing it its PHY. The CPU port would then point to the
> internal switch PHY.

Is it really a back-to-back PHY? If that is the case, ok, that can
indeed work without magnetics, but this is really an inefficient way to
connect a MAC to a switch, especially when you can do direct (R)GMII
without any PHY in between... If that is the case, then disregard my
comment.

> 
> Or are you suggesting the i210 has two phy-handles, its own and the
> switches?

Not suggesting that, that would be weird.

> 
> 	Andrew
> 


-- 
Florian