Re: [PATCH 1/2] riscv: dts: sophgo: Enable ethernet for Milk-V Duo 256M

[葉宸佑]

On Sat, Aug 22, 2026 at 10:15:XX +0800, Inochi Amaoto wrote:
> This is not acceptable, I agree with something like DT overlay for
> support external IO board to enable this. But you should not enable
> this by default. As other may want to use this as GPIO.

You are right, and I should have caught this myself -- the signals only
go to the RJ45 on the optional IO board, so enabling them in the board
DTS takes the pins away from anyone who wants them as GPIO. Thanks for
stopping it.

I will rework this as a DT overlay for v2: the board DTS keeps the GMAC
and MDIO mux disabled, and a separate .dtso enables them for the USB &
Ethernet IO board [1].

One thing before I send it: I do not have the IO board yet, which is why
v1 said link-up was unverified. I have ordered one, so v2 will come with
an actual link-up and iperf3 result rather than just "the PHY is
detected". I would rather send it tested than send it soon.

[1] https://milkv.io/docs/duo/io-board/usb-ethernet-iob

Chen-Yu

Inochi Amaoto <inochiama@xxxxxxxxx> 於 2026年8月22日週六 上午10:13寫道：
>
> On Tue, Aug 04, 2026 at 12:33:18AM +0800, Chen-Yu Yeh wrote:
> > The SG2002 has an internal ethernet PHY, but on the Milk-V Duo 256M the
> > ethernet signals are only routed to the RJ45 connector of the optional
> > IO board.
> >
> > Enable the GMAC and the MDIO multiplexer so that the interface is usable
> > when such a board is attached.
> >
> > Tested on actual Milk-V Duo 256M hardware: the GMAC probes, the MDIO
> > multiplexer selects the internal bus and the internal EPHY is detected
> > at address 1:
> >
> >   eth0: PHY [mdio_mux-0.0:01] driver [Generic PHY]
> >
>
> > Link-up was not verified for lack of the IO board.
> >
>
> This is not acceptable, I agree with something like DT overlay for
> support external IO board to enable this. But you should not enable
> this by default. As other may want to use this as GPIO.
>
> Regards,
> Inochi
>
> > Signed-off-by: Chen-Yu Yeh <chenyou910331@xxxxxxxxx>
> > ---
> >  arch/riscv/boot/dts/sophgo/sg2002-milkv-duo256m.dts | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> >
> > diff --git a/arch/riscv/boot/dts/sophgo/sg2002-milkv-duo256m.dts b/arch/riscv/boot/dts/sophgo/sg2002-milkv-duo256m.dts
> > index a2797c0bd767..1462a96a1c12 100644
> > --- a/arch/riscv/boot/dts/sophgo/sg2002-milkv-duo256m.dts
> > +++ b/arch/riscv/boot/dts/sophgo/sg2002-milkv-duo256m.dts
> > @@ -49,6 +49,14 @@ coprocessor_rtos: region@8fe00000 {
> >       };
> >  };
> >
> > +&gmac0 {
> > +     status = "okay";
> > +};
> > +
> > +&mdio {
> > +     status = "okay";
> > +};
> > +
> >  &osc {
> >       clock-frequency = <25000000>;
> >  };
> >
> > base-commit: 11881041b745b444e4f6c87a2748f1951cf02742
> > --
> > 2.43.0
> >