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

[Vladimir Oltean]

On Mon, 17 Feb 2020 at 17:33, Vladimir Oltean <olteanv@xxxxxxxxx> wrote:
>
> 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?
>

To clarify, the reason I'm asking whether it matters is because I'd
have to modify PHY_INTERFACE_MODE_GMII in
drivers/net/dsa/ocelot/felix_vsc9959.c too, for the internal ports.
Then I'm not sure anymore what tree this device tree patch should go
in through.

> > > +                                             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