Re: [RFC PATCH 4/8] xilinx: tsn: Add Ethernet MAC (EMAC) and MDIO support to the TSN driver

[Andrew Lunn <andrew@lunn.ch>]

> +#define TSN_EMMC_LINKSPEED_10		0x0	   /* 10 Mbit */

If the MAC cannot do 10Mbps, why have this?

> +static int emac_open(struct net_device *ndev)
> +{
> +	struct tsn_emac *emac = netdev_priv(ndev);
> +	struct phy_device *phydev = NULL;
> +
> +	if (emac->phy_node) {
> +		phydev = of_phy_connect(emac->ndev, emac->phy_node,
> +					tsn_adjust_link_tsn,
> +					emac->phy_flags,
> +					emac->phy_mode);
> +		if (!phydev)
> +			dev_err(emac->common->dev, "of_phy_connect() failed\n");
> +		else
> +			phy_start(phydev);
> +	}

Somewhere around here, i would expect you to tell phylib the MAC
cannot do 10Mbps. You don't want the PHY offering those speeds for
autoneg, otherwise it might actually negotiate 10Mbps.

I also think you should be using phylink, not phylib. But we first
need to finish the discussion about DSA vs pure switchdev. If this
ends up being a DSA driver, you will be using phylink anywhere. If it
is a pure switchdev driver, i would still recommend using phylink, you
are less likely to get things wrong, because the API is better
designed.

    Andrew