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    SubjectRe: [PATCH] net: phy: realtek: Add rtl8211e rx/tx delays config
    On Fri, Apr 26, 2019 at 12:30:10PM +0300, Serge Semin wrote:
    > The hidden RGMII configs register utilization was found in the
    > rtl8211e U-boot driver:
    > https://elixir.bootlin.com/u-boot/v2019.01/source/drivers/net/phy/realtek.c#L99
    >
    > It confirms that the register bits field must control the so called
    > configuration pins described in the table 12-13 of the official PHY
    > datasheet:
    > 8:6 = PHY Address
    > 5:4 = Auto-Negotiation
    > 3 = Interface Mode Select
    > 2 = RX Delay
    > 1 = TX Delay
    > 0 = SELRGV

    > +static int rtl8211e_config_init(struct phy_device *phydev)
    > +{
    > + int ret, oldpage;
    > + u16 val = 0;
    > +
    > + ret = genphy_config_init(phydev);
    > + if (ret < 0)
    > + return ret;
    > +
    > + /* enable TX/RX delay for rgmii-* modes, otherwise disable it */
    > + if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID)
    > + val = RTL8211E_TX_DELAY | RTL8211E_RX_DELAY;
    > + else if (phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID)
    > + val = RTL8211E_TX_DELAY;
    > + else if (phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID)
    > + val = RTL8211E_RX_DELAY;

    Hi Serge

    You need to look for PHY_INTERFACE_MODE_RGMII and disable the bits.
    For any other value, and in particular PHY_INTERFACE_MODE_NA, you
    should leave the bits alone.

    As you found out, u-boot knows how to program these bits. There are
    probably boards out there which rely on u-boot doing this, and the PHY
    driver then not messing with the bits. The way to indicate it should
    not mess with the bits is to not have a phy-mode property in DT, which
    results in PHY_INTERFACE_MODE_NA.

    Andrew

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