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From:   =?UTF-8?B?Q2zDqW1lbnQgUMOpcm9u?= <peron.clem@gmail.com>
Date:   Sat, 24 Oct 2020 21:09:52 +0200
Message-ID: <CAJiuCccANajJbXqJ8mrOzL0jFdsbrrtFbMqfrqPAWEt6pBMNSA@mail.gmail.com>
Subject: Re: [linux-sunxi] [PATCH 02/10] ARM: dts: sun6i: a31-hummingbird:
 Enable RGMII RX/TX delay on Ethernet PHY
To:     Icenowy Zheng <icenowy@aosc.io>
Cc:     =?UTF-8?Q?Jernej_=C5=A0krabec?= <jernej.skrabec@siol.net>,
        Chen-Yu Tsai <wens@kernel.org>,
        Maxime Ripard <mripard@kernel.org>,
        linux-sunxi <linux-sunxi@googlegroups.com>,
        Chen-Yu Tsai <wens@csie.org>,
        devicetree <devicetree@vger.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        linux-kernel <linux-kernel@vger.kernel.org>
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Hi,

On Sat, 24 Oct 2020 at 20:39, Icenowy Zheng <icenowy@aosc.io> wrote:
>
>
>
> =E4=BA=8E 2020=E5=B9=B410=E6=9C=8825=E6=97=A5 GMT+08:00 =E4=B8=8A=E5=8D=
=882:30:35, "Jernej =C5=A0krabec" <jernej.skrabec@siol.net> =E5=86=99=E5=88=
=B0:
> >Dne sobota, 24. oktober 2020 ob 19:51:06 CEST je Icenowy Zheng
> >napisal(a):
> >> =E5=9C=A8 2020-10-25=E6=98=9F=E6=9C=9F=E6=97=A5=E7=9A=84 00:25 +0800=
=EF=BC=8CChen-Yu Tsai=E5=86=99=E9=81=93=EF=BC=9A
> >>
> >> > From: Chen-Yu Tsai <wens@csie.org>
> >> >
> >> > The Ethernet PHY on the A31 Hummingbird has the RX and TX delays
> >> > enabled on the PHY, using pull-ups on the RXDLY and TXDLY pins.
> >> >
> >> > Fix the phy-mode description to correct reflect this so that the
> >> > implementation doesn't reconfigure the delays incorrectly. This
> >> > happened with commit bbc4d71d6354 ("net: phy: realtek: fix rtl8211e
> >> > rx/tx delay config").
> >>
> >> Personally I think they should revert this commit, and consider other
> >> solution.
> >>
> >> This commit breaks everything.
> >>
> >
> >Previously broken driver allowed inproper DT to work, so you have to
> >fix
> >everything eventually.
>
> There is no "improper DT" if it's already shipped, DT should suffer drive=
r
> change, not changed to match driver.
>
> I think at least Fedora tends to ship a DT with a system image that will
> not get updated when kernel gets updated.

I think we are missing a phy-mode saying use RGMII but don't change
the delay set by the hardware.
Or maybe introduce a phy-mode=3D'rgmii-noid' to explicitly disable the
RX/TD delay using software bits
and use phy-mode=3D'rgmii' to keep the delay set by the hardware.

Clement

>
> >
> >Plus side, there is no need to have hack for Pine64 Plus ethernet
> >anymore.
> >
> >Best regards,
> >Jernej
> >
> >> (Although the patch on individual DT patches are technically correct)
> >>
> >> > Fixes: c220aec2bb79 ("ARM: dts: sun6i: Add Merrii A31 Hummingbird
> >> > support")
> >> > Signed-off-by: Chen-Yu Tsai <wens@csie.org>
> >> > ---
> >> >
> >> >  arch/arm/boot/dts/sun6i-a31-hummingbird.dts | 2 +-
> >> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >> >
> >> > diff --git a/arch/arm/boot/dts/sun6i-a31-hummingbird.dts
> >> > b/arch/arm/boot/dts/sun6i-a31-hummingbird.dts
> >> > index 049e6ab3cf56..73de34ae37fd 100644
> >> > --- a/arch/arm/boot/dts/sun6i-a31-hummingbird.dts
> >> > +++ b/arch/arm/boot/dts/sun6i-a31-hummingbird.dts
> >> > @@ -154,7 +154,7 @@ &gmac {
> >> >
> >> >    pinctrl-names =3D "default";
> >> >    pinctrl-0 =3D <&gmac_rgmii_pins>;
> >> >    phy-handle =3D <&phy1>;
> >> >
> >> > -  phy-mode =3D "rgmii";
> >> > +  phy-mode =3D "rgmii-id";
> >> >
> >> >    status =3D "okay";
> >> >
> >> >  };
>
> --
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