net: enetc: kill PHY-less mode for PFs

Right now, a PHY-less port (no phy-mode, no fixed-link, no phy-handle)
doesn't register with phylink, but calls netif_carrier_on() from
enetc_start().

This makes sense for a VF, but for a PF, this is braindead, because we
never call enetc_mac_enable() so the MAC is left inoperational.
Furthermore, commit 71b77a7a ("enetc: Migrate to PHYLINK and
PCS_LYNX") put the nail in the coffin because it removed the initial
netif_carrier_off() call done right after register_netdev().

Without that call, netif_carrier_on() does not call
linkwatch_fire_event(), so the operstate remains IF_OPER_UNKNOWN.

Just deny the broken configuration by requiring that a phy-mode is
present, and always register a PF with phylink.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Claudiu Manoil <claudiu.manoil@nxp.com>
Link: https://lore.kernel.org/r/20220511094200.558502-1-vladimir.oltean@nxp.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/net/ethernet/freescale/enetc/enetc_pf.c

@@ -1105,8 +1105,7 @@ static int enetc_phylink_create(struct enetc_ndev_priv *priv,
 
 static void enetc_phylink_destroy(struct enetc_ndev_priv *priv)
 {
-	if (priv->phylink)
-		phylink_destroy(priv->phylink);
+	phylink_destroy(priv->phylink);
 }
 
 /* Initialize the entire shared memory for the flow steering entries
@@ -1273,16 +1272,20 @@ static int enetc_pf_probe(struct pci_dev *pdev,
 		goto err_alloc_msix;
 	}
 
-	if (!of_get_phy_mode(node, &pf->if_mode)) {
-		err = enetc_mdiobus_create(pf, node);
-		if (err)
-			goto err_mdiobus_create;
-
-		err = enetc_phylink_create(priv, node);
-		if (err)
-			goto err_phylink_create;
+	err = of_get_phy_mode(node, &pf->if_mode);
+	if (err) {
+		dev_err(&pdev->dev, "Failed to read PHY mode\n");
+		goto err_phy_mode;
 	}
 
+	err = enetc_mdiobus_create(pf, node);
+	if (err)
+		goto err_mdiobus_create;
+
+	err = enetc_phylink_create(priv, node);
+	if (err)
+		goto err_phylink_create;
+
 	err = register_netdev(ndev);
 	if (err)
 		goto err_reg_netdev;
@@ -1294,6 +1297,7 @@ static int enetc_pf_probe(struct pci_dev *pdev,
 err_phylink_create:
 	enetc_mdiobus_destroy(pf);
 err_mdiobus_create:
+err_phy_mode:
 	enetc_free_msix(priv);
 err_config_si:
 err_alloc_msix: