netdev - Re: [RESENT PATCH net--stat 1/1] net: ethernet: fec: Revert "net: ethernet: fec: Replace interrupt driven MDIO with polled IO"

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Message-ID: <CAFXsbZrysb6SGisEhgXHzj8NZ5o_EjY-rtiqg3gypgr0w-d-dw@mail.gmail.com>
Date:   Sun, 26 Jul 2020 19:40:11 -0700
From:   Chris Healy <cphealy@...il.com>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:     Andrew Lunn <andrew@...n.ch>, Fugang Duan <fugang.duan@....com>,
        "David S. Miller" <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>,
        Martin Fuzzey <martin.fuzzey@...wbird.group>
Subject: Re: [RESENT PATCH net--stat 1/1] net: ethernet: fec: Revert "net:
 ethernet: fec: Replace interrupt driven MDIO with polled IO"

Actually, I was a little quick to say it went from broken to working.

With net-next, I'm getting CRC errors on 100% of inbound packets.
With bcf3440c6dd78bfe5836ec0990fe36d7b4bb7d20 reverted, I drop down to
a 1% error rate.

This very much feels like a KSZ9031 RGMII timing issue to me...

On Sun, Jul 26, 2020 at 7:35 PM Chris Healy <cphealy@...il.com> wrote:
>
> Hi Laurent,
>
> I have the exact same copper PHY.  I just reverted a patch specific to
> this PHY and went from broken to working.  Give this a try:
>
> git revert bcf3440c6dd78bfe5836ec0990fe36d7b4bb7d20
>
> Regards,
>
> Chris
>
> On Sun, Jul 26, 2020 at 7:33 PM Laurent Pinchart
> <laurent.pinchart@...asonboard.com> wrote:
> >
> > Hi Andrew,
> >
> > On Mon, Jul 27, 2020 at 04:14:32AM +0200, Andrew Lunn wrote:
> > > On Mon, Jul 27, 2020 at 05:06:31AM +0300, Laurent Pinchart wrote:
> > > > On Mon, Jul 27, 2020 at 04:24:02AM +0300, Laurent Pinchart wrote:
> > > > > On Mon, Apr 27, 2020 at 10:08:04PM +0800, Fugang Duan wrote:
> > > > > > This reverts commit 29ae6bd1b0d8a57d7c00ab12cbb949fc41986eef.
> > > > > >
> > > > > > The commit breaks ethernet function on i.MX6SX, i.MX7D, i.MX8MM,
> > > > > > i.MX8MQ, and i.MX8QXP platforms. Boot yocto system by NFS mounting
> > > > > > rootfs will be failed with the commit.
> > > > >
> > > > > I'm afraid this commit breaks networking on i.MX7D for me :-( My board
> > > > > is configured to boot over NFS root with IP autoconfiguration through
> > > > > DHCP. The DHCP request goes out, the reply it sent back by the server,
> > > > > but never noticed by the fec driver.
> > > > >
> > > > > v5.7 works fine. As 29ae6bd1b0d8a57d7c00ab12cbb949fc41986eef was merged
> > > > > during the v5.8 merge window, I suspect something else cropped in
> > > > > between 29ae6bd1b0d8a57d7c00ab12cbb949fc41986eef and this patch that
> > > > > needs to be reverted too. We're close to v5.8 and it would be annoying
> > > > > to see this regression ending up in the released kernel. I can test
> > > > > patches, but I'm not familiar enough with the driver (or the networking
> > > > > subsystem) to fix the issue myself.
> > > >
> > > > If it can be of any help, I've confirmed that, to get the network back
> > > > to usable state from v5.8-rc6, I have to revert all patches up to this
> > > > one. This is the top of my branch, on top of v5.8-rc6:
> > > >
> > > > 5bbe80c9efea Revert "net: ethernet: fec: Revert "net: ethernet: fec: Replace interrupt driven MDIO with polled IO""
> > > > 5462896a08c1 Revert "net: ethernet: fec: Replace interrupt driven MDIO with polled IO"
> > > > 824a82e2bdfa Revert "net: ethernet: fec: move GPR register offset and bit into DT"
> > > > bfe330591cab Revert "net: fec: disable correct clk in the err path of fec_enet_clk_enable"
> > > > 109958cad578 Revert "net: ethernet: fec: prevent tx starvation under high rx load"
> > >
> > > OK.
> > >
> > > What PHY are you using? A Micrel?
> >
> > KSZ9031RNXIA
> >
> > > And which DT file?
> >
> > It's out of tree.
> >
> > &fec1 {
> >         pinctrl-names = "default";
> >         pinctrl-0 = <&pinctrl_enet1>;
> >         assigned-clocks = <&clks IMX7D_ENET1_TIME_ROOT_SRC>,
> >                           <&clks IMX7D_ENET1_TIME_ROOT_CLK>;
> >         assigned-clock-parents = <&clks IMX7D_PLL_ENET_MAIN_100M_CLK>;
> >         assigned-clock-rates = <0>, <100000000>;
> >         phy-mode = "rgmii";
> >         phy-handle = <&ethphy0>;
> >         phy-reset-gpios = <&gpio1 13 GPIO_ACTIVE_LOW>;
> >         phy-supply = <&reg_3v3_sw>;
> >         fsl,magic-packet;
> >         status = "okay";
> >
> >         mdio {
> >                 #address-cells = <1>;
> >                 #size-cells = <0>;
> >
> >                 ethphy0: ethernet-phy@0 {
> >                         reg = <1>;
> >                 };
> >
> >                 ethphy1: ethernet-phy@1 {
> >                         reg = <2>;
> >                 };
> >         };
> > };
> >
> > I can provide the full DT if needed.
> >
> > --
> > Regards,
> >
> > Laurent Pinchart