Re: [PATCH 2/4] dt-bindings: net: dsa: document internal MDIO bus

Andrew Lunn
2023-09-09T21:16:37Z

Please trim the text when replying.

> I'm writing below as a mix of patch log and discussion.
>
> Phylink bindings are required for ports that are controlled by OF-based
> buses. DSA, like any other driver utilising the Linux MDIO infrastructure,
> can register a bus. If I understand correctly, non-OF-based registration of
> OpenFirmware MDIO buses is a feature specific to DSA which certain DSA
> subdrivers make use of.

This is not really DSA specific. Any MAC driver, or MDIO driver, can
call mdiobus_regsiter(), or of_mdiobus_register() and pass a NULL
pointer if there is no OF node available. It then requires that the
MAC driver uses an function like phy_find_first(), or knows via other
means what address the PHY uses on the bus. For DSA, that other means
is assuming a 1:1 mapping between port number and bus address.

Andrew