RE: [PATCH net-next 1/2] net: stmmac: enable 2.5Gbps link speed

[Voon, Weifeng]

> On Fri, Apr 02, 2021 at 07:45:04AM +0000, Voon, Weifeng wrote:
> > > > +	/* 2.5G mode only support 2500baseT full duplex only */
> > > > +	if (priv->plat->has_gmac4 && priv->plat->speed_2500_en) {
> > > > +		phylink_set(mac_supported, 2500baseT_Full);
> > > > +		phylink_set(mask, 10baseT_Half);
> > > > +		phylink_set(mask, 10baseT_Full);
> > > > +		phylink_set(mask, 100baseT_Half);
> > > > +		phylink_set(mask, 100baseT_Full);
> > > > +		phylink_set(mask, 1000baseT_Half);
> > > > +		phylink_set(mask, 1000baseT_Full);
> > > > +		phylink_set(mask, 1000baseKX_Full);
> > >
> > > Why? This seems at odds to the comment above?
> >
> > > What about 2500baseX_Full ?
> >
> > The comments explain that the PCS<->PHY link is in 2500BASE-X and why
> > 10/100/1000 link speed is mutually exclusive with 2500.
> > But the connected external PHY are twisted pair cable which only
> > supports 2500baseT_full.
> 
> The PHY should indicate what modes its supports. The PHY drivers
> get_features() call should set supported to only 2500baseT_Full, if that is
> all it supports.
> 
> What modes are actually used should then be the intersect of what both the
> MAC and the PHY indicate they can do.

Noted Andrew. Instead of masking the 10/100/1000 mode support in the MAC, we will
set the supported modes in the PCS.