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

[Jan Petrous]

Hi Chester,
 
> Hi Andrew and Andreas,
> 
> On Thu, Nov 03, 2022 at 11:05:30PM +0100, Andrew Lunn wrote:
> > > > > +      - description: Main GMAC clock
> > > > > +      - description: Peripheral registers clock
> > > > > +      - description: Transmit SGMII clock
> > > > > +      - description: Transmit RGMII clock
> > > > > +      - description: Transmit RMII clock
> > > > > +      - description: Transmit MII clock
> > > > > +      - description: Receive SGMII clock
> > > > > +      - description: Receive RGMII clock
> > > > > +      - description: Receive RMII clock
> > > > > +      - description: Receive MII clock
> > > > > +      - description:
> > > > > +          PTP reference clock. This clock is used for programming the
> > > > > +          Timestamp Addend Register. If not passed then the system
> > > > > +          clock will be used.
> >
> > > Not clear to me has been whether the PHY mode can be switched at
> runtime
> > > (like DPAA2 on Layerscape allows for SFPs) or whether this is fixed by
> board
> > > design.
> >
> > Does the hardware support 1000BaseX? Often the hardware implementing
> > SGMII can also do 1000BaseX, since SGMII is an extended/hacked up
> > 1000BaseX.
> >
> > If you have an SFP connected to the SERDES, a fibre module will want
> > 1000BaseX and a copper module will want SGMII. phylink will tell you
> > what phy-mode you need to use depending on what module is in the
> > socket. This however might be a mute point, since both of these are
> > probably using the SGMII clocks.
> >
> > Of the other MII modes listed, it is very unlikely a runtime swap will
> > occur.
> >
> >       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. 

/Jan

--
NXP Czechia, AP Ethernet