> +enum mii_mode { > + MII_MODE_MII = 0, > + MII_MODE_RGMII, > + MII_MODE_SGMII There is no mention of SGMII anywhere else. And in a couple of places, the code makes the assumption that if it is not RGMII it is MII. Does the hardware really support SGMII? > +static int prueth_config_rgmiidelay(struct prueth *prueth, > + struct device_node *eth_np, > + phy_interface_t phy_if) > +{ ... > + if (phy_if == PHY_INTERFACE_MODE_RGMII_ID || > + phy_if == PHY_INTERFACE_MODE_RGMII_TXID) > + rgmii_tx_id |= ICSSG_CTRL_RGMII_ID_MODE; > + > + regmap_update_bits(ctrl_mmr, icssgctrl_reg, ICSSG_CTRL_RGMII_ID_MODE, rgmii_tx_id); Here you are adding the TX delay if the phy-mode indicates it should be added. > +static int prueth_netdev_init(struct prueth *prueth, > + struct device_node *eth_node) > +{ > + ret = of_get_phy_mode(eth_node, &emac->phy_if); > + if (ret) { > + dev_err(prueth->dev, "could not get phy-mode property\n"); > + goto free; > + } > + ret = prueth_config_rgmiidelay(prueth, eth_node, emac->phy_if); > + if (ret) > + goto free; > + Reading it from DT and calling the delay function. > +static int prueth_probe(struct platform_device *pdev) > +{ > + /* register the network devices */ > + if (eth0_node) { > + ret = register_netdev(prueth->emac[PRUETH_MAC0]->ndev); > + if (ret) { > + dev_err(dev, "can't register netdev for port MII0"); > + goto netdev_exit; > + } > + > + prueth->registered_netdevs[PRUETH_MAC0] = prueth->emac[PRUETH_MAC0]->ndev; > + > + emac_phy_connect(prueth->emac[PRUETH_MAC0]); And this is connecting the MAC and the PHY, where emac_phy_connect() passes emac->phy_if to phylib. What i don't see anywhere is you changing emac->phy_if to indicate the MAC has inserted the TX delay, and so the PHY should not. Andrew