[EXT] Re: [PATCH v1 2/5] net: phy: marvell: extend 88E2110 to use both 2.5GHz modes

[Stefan Chulski]

> > What I am confused about is that this patch adds check for
> >   PHY_INTERFACE_MODE_SGMII_2500
> > in addition to
> >   PHY_INTERFACE_MODE_2500BASEX
> >
> > But what is the difference between these two?
> >
> > Marvell named this protocol HS-SGMII in some of their datasheets and
> > code. I guess this was done because of the similarities with 1000base-x and
> SGMII.
> > Marvell uses the names SGMII and 1000base-x interchangably, although
> > this is not correct. I guess they are similarily using names
> > 2500base-x and HS-SGMII (and now SGMII_2500) interchangably, which is
> also not correct.
> >
> > SGMII uses the same coding as 1000base-x, but the latter works only
> > with one speed (1000mbps), while the former can also work in 10mbps
> > and 100mbps (by repeating each byte 100 or 10 times, respectively).
> >
> > Then there is 2500base-x, which is the same as 1000base-x, but with
> > the clock being at 2.5x the speed of 1000base-x clock.
> >
> > But there is no analogue of the SGMII protocol (i.e. the repearing of
> > bytes in order to achieve lower speed) for the 2500base-x.
> >
> > So what I am confused about here is what is supposed to be the
> > difference between
> >   PHY_INTERFACE_MODE_SGMII_2500
> > and
> >   PHY_INTERFACE_MODE_2500BASEX
> > ?
> >
> > Marek

I not sure what is correct naming for these mode. PHY_INTERFACE includes both MAC2PHY interfaces(MII, RGMII and etc), PHY2PHY interfaces(like BASEX) and SGMII(which is kind of both).
For both 2500BASEX and SGMII_2500 Serdes lanes set to HS-SGMII in 3.125G speed, but MAC configured differently and autoneg cannot be supported.

Regards,
Stefan.