Re: [PATCH net-next v2 2/5] net: dsa: Initialize ds->enabled_port_mask and ds->phys_mii_mask

@@ -304,6 +312,18 @@ static int dsa_ds_apply(struct dsa_switch_tree *dst, struct dsa_switch *ds)
 	if (err < 0)
 		return err;
 
+	if (!ds->slave_mii_bus && ds->drv->phy_read) {
+		ds->slave_mii_bus = devm_mdiobus_alloc(ds->dev);
+		if (!ds->slave_mii_bus)
+			return err;
+
+		dsa_slave_mii_bus_init(ds);
+
+		err = mdiobus_register(ds->slave_mii_bus);
+		if (err < 0)
+			return err;
+	}
+
 	for (index = 0; index < DSA_MAX_PORTS; index++) {
 		port = ds->ports[index].dn;
 		if (!port)