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From:   Bruno Thomsen <bruno.thomsen@gmail.com>
Date:   Fri, 9 Oct 2020 16:25:49 +0200
Message-ID: <CAH+2xPD=CE+pk_cEC=cLv1nebBBg7X+xDpOFANf3rQ4V2+2Cvw@mail.gmail.com>
Subject: Re: PHY reset question
To:     Fabio Estevam <festevam@gmail.com>
Cc:     Oleksij Rempel <o.rempel@pengutronix.de>,
        Andrew Lunn <andrew@lunn.ch>, David Jander <david@protonic.nl>,
        Sascha Hauer <kernel@pengutronix.de>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        netdev <netdev@vger.kernel.org>,
        Russell King <linux@armlinux.org.uk>,
        Marc Kleine-Budde <mkl@pengutronix.de>,
        Marek Vasut <marex@denx.de>,
        Florian Fainelli <f.fainelli@gmail.com>
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Hi Fabio and Oleksij

Den ons. 7. okt. 2020 kl. 11.50 skrev Fabio Estevam <festevam@gmail.com>:
>
> Hi Oleksij,
>
> On Tue, Oct 6, 2020 at 5:05 AM Oleksij Rempel <o.rempel@pengutronix.de> wrote:
> >
> > Hello PHY experts,
> >
> > Short version:
> > what is the proper way to handle the PHY reset before identifying PHY?
> >
> > Long version:
> > I stumbled over following issue:
> > If PHY reset is registered within PHY node. Then, sometimes,  we will not be
> > able to identify it (read PHY ID), because PHY is under reset.
> >
> > mdio {
> >         compatible = "virtual,mdio-gpio";
> >
> >         [...]
> >
> >         /* Microchip KSZ8081 */
> >         usbeth_phy: ethernet-phy@3 {
> >                 reg = <0x3>;
> >
> >                 interrupts-extended = <&gpio5 12 IRQ_TYPE_LEVEL_LOW>;
> >                 reset-gpios = <&gpio5 11 GPIO_ACTIVE_LOW>;
> >                 reset-assert-us = <500>;
> >                 reset-deassert-us = <1000>;
> >         };
> >
> >         [...]
> > };
> >
> > On simple boards with one PHY per MDIO bus, it is easy to workaround by using
> > phy-reset-gpios withing MAC node (illustrated in below DT example), instead of
> > using reset-gpios within PHY node (see above DT example).
> >
> > &fec {
> >         [...]
> >         phy-mode = "rmii";
> >         phy-reset-gpios = <&gpio4 12 GPIO_ACTIVE_LOW>;
> >         [...]
>
> I thought this has been fixed by Bruno's series:
> https://www.spinics.net/lists/netdev/msg673611.html

Yes, that has fixed the Microchip/Micrel PHY ID auto detection
issue. I have send a DTS patch v3 that makes use of the newly
added device tree parameter:
https://lkml.org/lkml/2020/9/23/595

/Bruno