Handle phys changing the interface between 2500basex & SGMII

Handle phys changing the interface between 2500basex & SGMII

[Alexander 'lynxis' Couzens]

Hi,

I've a mediatek mt7622 SoC connected to a realtek 2.5gbit copper phy
(rtl8221) via SGMII/2500basex.

The rtl8221 is changing its phy interface depending on the link.
So 2500basex for 2.5gbit copper and for all lower speeds (down to
10mbit) it's using SGMII.

What's the best way to implement it?
Should the phy driver change the phy_interface on link up?

As a hack I've modified mac_link_up to handle the different speeds
and changed the phylink_mac_ops validate to allow advertising lower
speeds on 2500basex.

Best,
lynxis

Re: Handle phys changing the interface between 2500basex & SGMII

[Andrew Lunn]

On Mon, Sep 19, 2022 at 04:47:13PM +0200, Alexander 'lynxis' Couzens wrote:
> Hi,
> 
> I've a mediatek mt7622 SoC connected to a realtek 2.5gbit copper phy
> (rtl8221) via SGMII/2500basex.
> 
> The rtl8221 is changing its phy interface depending on the link.
> So 2500basex for 2.5gbit copper and for all lower speeds (down to
> 10mbit) it's using SGMII.
> 
> What's the best way to implement it?

The marvel10g PHY driver is a good example to follow. It also changes
its host side interface mode as needed by whatever the copper side has
negotiated.

> Should the phy driver change the phy_interface on link up?

Yes.

> As a hack I've modified mac_link_up to handle the different speeds
> and changed the phylink_mac_ops validate to allow advertising lower
> speeds on 2500basex.

phylink should not need any changes. You just need your MAC driver to
follow what is happening in its callbacks.

       Andrew