[EXT] Re: [PATCH 2/5] dt-bindings: net: add schema for NXP S32CC dwmac glue driver

[Jan Petrous]

Hi Andrew,

> > > Here I just focus on GMAC since there are other LAN interfaces that S32
> > > family
> > > uses [e.g. PFE]. According to the public GMACSUBSYS ref manual rev2[1]
> > > provided
> > > on NXP website, theoretically GMAC can run SGMII in 1000Mbps and
> > > 2500Mbps so I
> > > assume that supporting 1000BASE-X could be achievable. I'm not sure if
> any
> > > S32
> > > board variant might have SFP ports but RJ-45 [1000BASE-T] should be the
> > > major
> > > type used on S32G-EVB and S32G-RDB2.
> > >
> > > @NXP, please feel free to correct me if anything wrong.
> > >
> >
> > NXP eval boards (EVB or RDB) have also 2.5G PHYs, so together with SerDes
> > driver we support 100M/1G/2.5G on such copper PHYs.
> 
> Hi Jan
> 
> Does the SERDES clock need to change when going between 1000BaseX and
> 2500BaseX?
> 
> If so, it sounds like Linux not having control of that clock is going
> to limit what can be supported.

No, the SerDes clock remains the same, the change is done internally, without
any necessity of clock change intervention by GMAC driver.

/Jan