Subject: Re: [PATCH RFC net-next 0/4] net: dsa: always use phylink

From: Marek Behún <[email-masked]>
Date: Wed, 29 Jun 2022 11:27:50 +0200

On Wed, 29 Jun 2022 09:18:10 +0200
Andrew Lunn <[email-masked]> wrote:

> > I should point out that if a DSA port can be programmed in software to
> > support both SGMII and 1000baseX, this will end up selecting SGMII
> > irrespective of what the hardware was wire-strapped to and how it was
> > initially configured. Do we believe that would be acceptable?  
> 
> I'm pretty sure the devel b board has 1000BaseX DSA links between its
> two switches. Since both should end up SGMII that should be O.K.
> 
> Where we potentially have issues is 1000BaseX to the CPU. This is not
> an issue for the Vybrid based boards, since they are fast Ethernet
> only, but there are some boards with an IMX6 with 1G ethernet. I guess
> they currently use 1000BaseX, and the CPU side of the link probably
> has a fixed-link with phy-mode = 1000BaseX. So we might have an issue
> there.

If one side of the link (e.g. only the CPU eth interface) has 1000base-x
specified in device-tree explicitly, the code should keep it at
1000base-x for the DSA CPU port...

Marek