netdev - Re: [PATCH net-next 4/5] tsnep: Add TSN endpoint Ethernet MAC driver

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Message-ID: <CANr-f5xOn1VcKZQNfb+iunHjq+8uUkxNQb0F1_gkjqd4CxGKDQ@mail.gmail.com>
Date:   Tue, 27 Jul 2021 22:49:27 +0200
From:   Gerhard Engleder <gerhard@...leder-embedded.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        netdev <netdev@...r.kernel.org>, devicetree@...r.kernel.org
Subject: Re: [PATCH net-next 4/5] tsnep: Add TSN endpoint Ethernet MAC driver

On Mon, Jul 26, 2021 at 11:15 PM Andrew Lunn <andrew@...n.ch> wrote:
> > +static int tsnep_mdiobus_read(struct mii_bus *bus, int addr, int regnum)
> > +{
> > +     struct tsnep_adapter *adapter = bus->priv;
> > +     u16 data;
> > +     int retval;
> > +
> > +     if (adapter->loopback)
> > +             return 0;
> > +
> > +     retval = tsnep_read_md(adapter, addr, regnum, &data);
> > +     if (retval != 0)
> > +             return retval;
>
> It appears your MDIO bus can only do C22. Please add a test for C45 and return -EOPNOTSUPP.

You are right. I will add that check.

> > +static void tsnep_phy_link_status_change(struct net_device *netdev)
> > +{
> > +     struct tsnep_adapter *adapter = netdev_priv(netdev);
> > +     struct phy_device *phydev = netdev->phydev;
> > +
> > +     if (adapter->loopback)
> > +             return;
> > +
> > +     if (adapter->gmii2rgmii) {
> > +             u16 val;
> > +
> > +             if (phydev->link && phydev->speed == 1000)
> > +                     val = BMCR_SPEED1000;
> > +             else
> > +                     val = BMCR_SPEED100;
> > +             tsnep_write_md(adapter, ECM_GMII2RGMII_ADDR,
> > +                            ECM_GMII2RGMII_BMCR, val);
> > +     }
>
> I _think_ this is wrong. They way the PHYs are chained means you
> should not need to do this, the xgmiitorgmii_read_status() does it.
> Maybe you have the chaining setup wrong?

I will try to use xgmiitorgmii.

> > +static int tsnep_phy_open(struct tsnep_adapter *adapter)
> > +{
> > +     __ETHTOOL_DECLARE_LINK_MODE_MASK(mask);
> > +     struct ethtool_eee ethtool_eee;
> > +     int retval;
> > +
> > +     retval = phy_connect_direct(adapter->netdev, adapter->phydev,
> > +                                 tsnep_phy_link_status_change,
> > +                                 adapter->phy_mode);
> > +     if (retval)
> > +             return -EIO;
>
> phy_connect_direct() returns an error code. Use it, rather than
> changing it to something else. This applies everywhere. You must have
> a good reason to change error codes, and then it is wise to put a
> comment why you change it.

I will fix it.

> > +
> > +     /* MAC supports only 100Mbps|1000Mbps full duplex
> > +      * SPE (Single Pair Ethernet) is also an option but not implemented yet
> > +      */
> > +     linkmode_zero(mask);
> > +     linkmode_set_bit(ETHTOOL_LINK_MODE_Autoneg_BIT, mask);
> > +     linkmode_set_bit(ETHTOOL_LINK_MODE_100baseT_Full_BIT, mask);
> > +     linkmode_set_bit(ETHTOOL_LINK_MODE_1000baseT_Full_BIT, mask);
> > +     linkmode_and(mask, adapter->phydev->supported, mask);
> > +     linkmode_copy(adapter->phydev->supported, mask);
> > +     linkmode_copy(adapter->phydev->advertising, mask);
>
> You should not be accessing the phydev directly. Use
> phy_remove_link_mode(phydev, ETHTOOL_LINK_MODE_1000baseT_Half_BIT),
> etc.I will try to use xgmiitorgmii.

I will use phy_remove_link_mode().

> > +static int tsnep_phy_init(struct tsnep_adapter *adapter)
> > +{
> > +     struct device_node *dn;
> > +     u16 val;
> > +     u32 id;
> > +     int retval;
> > +
> > +     retval = of_get_phy_mode(adapter->pdev->dev.of_node,
> > +                              &adapter->phy_mode);
> > +     if (retval)
> > +             adapter->phy_mode = PHY_INTERFACE_MODE_GMII;
> > +
> > +     dn = of_parse_phandle(adapter->pdev->dev.of_node, "phy-handle", 0);
> > +     adapter->phydev = of_phy_find_device(dn);
> > +     if (!adapter->phydev)
> > +             adapter->phydev = phy_find_first(adapter->mdiobus);
> > +     if (!adapter->phydev)
> > +             return -EIO;
> > +
> > +     /* detect optional GMII2RGMII */I will try to use xgmiitorgmii.
> > +     retval = tsnep_read_md(adapter, ECM_GMII2RGMII_ADDR, MII_PHYSID1, &val);
> > +     if (retval)
> > +             return retval;
> > +     id = val << 16;
> > +     retval = tsnep_read_md(adapter, ECM_GMII2RGMII_ADDR, MII_PHYSID2, &val);
> > +     if (retval)
> > +             return retval;
> > +     id |= val;
> > +     if (id == 0)
> > +             adapter->gmii2rgmii = true;
>
> This is where i think GMII2RGMII goes wrong. MAC phy-handle should
> point to the GMII2RGMII device in DT. The GMII2RGMII should have a
> phy-handle which points to the PHY.

As mentioned above, I will try to use xgmiitorgmii.

> > +     /* reset PHY */
> > +     retval = tsnep_write_md(adapter, adapter->phydev->mdio.addr, MII_BMCR,
> > +                             BMCR_RESET);
> > +     if (retval)
> > +             return retval;
> > +
> > +     /* reset GMII2RGMII */
> > +     if (adapter->gmii2rgmii) {
> > +             retval = tsnep_write_md(adapter, ECM_GMII2RGMII_ADDR,
> > +                                     ECM_GMII2RGMII_BMCR, BMCR_RESET);
> > +             if (retval)
> > +                     return retval;
> > +             retval = tsnep_write_md(adapter, ECM_GMII2RGMII_ADDR,
> > +                                     ECM_GMII2RGMII_BMCR, BMCR_SPEED100);
> > +             if (retval)
> > +                     return retval;
> > +     }
>
> The PHY driver is in control of the PHY, not the MAC. Please remove.

Ok, I will do that.

Gerhard