Re: [RFC net-next v2 0/6] ethtool: Generic loopback support

[Andrew Lunn]

> > > With a SERDES component, the mapping becomes cleaner:
> > >   component  name         supported
> > >   MAC        mac          near-end
> > >   SERDES     serdes-ned   near-end
> > >   SERDES     serdes-nea   near-end
> > >   SERDES     serdes-fed   far-end
> > 
> > If Linux where to drive the SERDES, what part of Linux would it be?
> > Generic PHY? How does your SERDES hardware block fit into 802.3? Which
> > clause describes it?
> 
> Hi Andrew,
> 
> On OcteonTx2 SoC, the SerDes (GSERM) is a HW block integrated into the
> SoC die. It is not on an MDIO bus or any bus that Linux can enumerate.
> The block is fully managed by the firmware running on the SoC. The NIC
> driver configures it indirectly through firmware mailbox commands.
> 
> The data path looks like:
>   MAC (RPM) --- SerDes (GSERM) --- module/PHY
> 
> In 802.3 terms, the closest match would be PMA. The GSERM handles
> serialization/deserialization and the analog front-end.

A Linux Generic PHY is probably also PMA.

802.3 says very little about SERDES, it is not a well defined term. So
i think we want PCS and PMA, not SERDES as a loopback point.

       Andrew