linux-kernel - Re: [PATCH v2 4/4] arm64: dts: allwinner: a133-liontron-h-a133l: Add Ethernet support

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Message-ID: <aG0bqasOYUwwgiQY@collins>
Date: Tue, 8 Jul 2025 15:22:49 +0200
From: Paul Kocialkowski <paulk@...-base.io>
To: Chen-Yu Tsai <wens@...e.org>
Cc: Andre Przywara <andre.przywara@....com>, devicetree@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-sunxi@...ts.linux.dev,
	linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Jernej Skrabec <jernej.skrabec@...il.com>,
	Samuel Holland <samuel@...lland.org>,
	Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH v2 4/4] arm64: dts: allwinner: a133-liontron-h-a133l: Add
 Ethernet support

Hi,

Le Tue 08 Jul 25, 16:18, Chen-Yu Tsai a écrit :
> On Tue, Jul 8, 2025 at 7:36 AM Andre Przywara <andre.przywara@....com> wrote:
> >
> > On Mon,  7 Jul 2025 18:51:55 +0200
> > Paul Kocialkowski <paulk@...-base.io> wrote:
> >
> > Hi Paul,
> >
> > > The Liontron H-A133L board features an Ethernet controller with a
> > > JLSemi JL1101 PHY. Its reset pin is tied to the PH12 GPIO.
> > >
> > > Note that the reset pin must be handled as a bus-wide reset GPIO in
> > > order to let the MDIO core properly reset it before trying to read
> > > its identification registers. There's no other device on the MDIO bus.
> >
> > putting the PHY reset GPIO into the MDIO node is a clever solution, I
> > was struggling with putting it either in the MAC or PHY node, though
> > conceptually it would still belong in the latter, I think. But this
> > might be a more generic problem: for most other devices we activate
> > reset and clock gates *before* trying to access them, though this might
> > be historically different for Ethernet PHYs.
> 
> The phylib core has code to deal with reset GPIOs listed under the PHY node.
> It might be worth checking why that doesn't work.

While this code does exist, it's too early to be called when the mdio bus is
trying to probe the phy. I was also surprised the existing reset gpio support
in the phylib core didn't take effect (that's how I tried to implement it first)
only to find that the code was never called. It's only called once the phy was
probed and registered.

Cheers,

Paul

> OOTH, there's no code to deal with regulator supplies for PHYs.
> 
> ChenYu
> 
> > > The datasheet of the PHY mentions that the reset signal must be held
> > > for 1 ms to take effect. Make it 2 ms (and the same for post-delay) to
> > > be on the safe side without wasting too much time during boot.
> > >
> > > Signed-off-by: Paul Kocialkowski <paulk@...-base.io>
> >
> > Despite the above, this looks fine, and works for me:
> >
> > Reviewed-by: Andre Przywara <andre.przywara@....com>
> > Tested-by: Andre Przywara <andre.przywara@....com>
> >
> > Cheers,
> > Andre
> >
> > > ---
> > >  .../sun50i-a133-liontron-h-a133l.dts          | 19 +++++++++++++++++++
> > >  1 file changed, 19 insertions(+)
> > >
> > > diff --git a/arch/arm64/boot/dts/allwinner/sun50i-a133-liontron-h-a133l.dts b/arch/arm64/boot/dts/allwinner/sun50i-a133-liontron-h-a133l.dts
> > > index fe77178d3e33..90a50910f07b 100644
> > > --- a/arch/arm64/boot/dts/allwinner/sun50i-a133-liontron-h-a133l.dts
> > > +++ b/arch/arm64/boot/dts/allwinner/sun50i-a133-liontron-h-a133l.dts
> > > @@ -65,6 +65,25 @@ &ehci1 {
> > >       status = "okay";
> > >  };
> > >
> > > +&emac0 {
> > > +     pinctrl-names = "default";
> > > +     pinctrl-0 = <&rmii0_pins>;
> > > +     phy-handle = <&rmii_phy>;
> > > +     phy-mode = "rmii";
> > > +     status = "okay";
> > > +};
> > > +
> > > +&mdio0 {
> > > +     reset-gpios = <&pio 7 12 GPIO_ACTIVE_LOW>; /* PH12 */
> > > +     reset-delay-us = <2000>;
> > > +     reset-post-delay-us = <2000>;
> > > +
> > > +     rmii_phy: ethernet-phy@1 {
> > > +             compatible = "ethernet-phy-ieee802.3-c22";
> > > +             reg = <1>;
> > > +     };
> > > +};
> > > +
> > >  &mmc0 {
> > >       vmmc-supply = <&reg_dcdc1>;
> > >       cd-gpios = <&pio 5 6 GPIO_ACTIVE_LOW>; /* PF6 */
> >
> >

-- 
Paul Kocialkowski,

Independent contractor - sys-base - https://www.sys-base.io/
Free software developer - https://www.paulk.fr/

Expert in multimedia, graphics and embedded hardware support with Linux.

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