Re: [PATCH devicetree 3/4] arm64: dts: fsl: ls1028a: add node for Felix switch

[Vladimir Oltean]

Hi Andrew,

On Mon, 17 Feb 2020 at 17:29, Andrew Lunn <andrew@xxxxxxx> wrote:
>
> Hi Vladimir
>
> > +                                     /* Internal port with DSA tagging */
> > +                                     mscc_felix_port4: port@4 {
> > +                                             reg = <4>;
> > +                                             phy-mode = "gmii";
>
> Is it really using gmii? Often in SoC connections use something else,
> and phy-mode = "internal" is more appropriate.
>

What would be that "something else"? Given that the host port and the
switch are completely different hardware IP blocks, I would assume
that a parallel GMII is what's connecting them, no optimizations done.
Certainly no serializer. But I don't know for sure.
Does it matter, in the end?

> > +                                             ethernet = <&enetc_port2>;
> > +
> > +                                             fixed-link {
> > +                                                     speed = <2500>;
> > +                                                     full-duplex;
> > +                                             };
>
> gmii and 2500 also don't really go together.

Not even if you raise the clock frequency?

>
>      Andrew

Thanks,
-Vladimir