net: dsa: PHY device is mandatory for EEE

The port's PHY and MAC are both implied in EEE. The current code does
not call the PHY operations if the related device is NULL. Change that
by returning -ENODEV if there's no PHY device attached to the interface.
Signed-off-by: NVivien Didelot <vivien.didelot@savoirfairelinux.com>
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
Reviewed-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/dsa/slave.c

@@ -648,6 +648,10 @@ static int dsa_slave_set_eee(struct net_device *dev, struct ethtool_eee *e)
 	struct dsa_switch *ds = p->dp->ds;
 	int ret;
 
+	/* Port's PHY and MAC both need to be EEE capable */
+	if (!p->phy)
+		return -ENODEV;
+
 	if (!ds->ops->set_eee)
 		return -EOPNOTSUPP;
 
@@ -655,10 +659,7 @@ static int dsa_slave_set_eee(struct net_device *dev, struct ethtool_eee *e)
 	if (ret)
 		return ret;
 
-	if (p->phy)
-		ret = phy_ethtool_set_eee(p->phy, e);
-
-	return ret;
+	return phy_ethtool_set_eee(p->phy, e);
 }
 
 static int dsa_slave_get_eee(struct net_device *dev, struct ethtool_eee *e)
@@ -667,6 +668,10 @@ static int dsa_slave_get_eee(struct net_device *dev, struct ethtool_eee *e)
 	struct dsa_switch *ds = p->dp->ds;
 	int ret;
 
+	/* Port's PHY and MAC both need to be EEE capable */
+	if (!p->phy)
+		return -ENODEV;
+
 	if (!ds->ops->get_eee)
 		return -EOPNOTSUPP;
 
@@ -674,10 +679,7 @@ static int dsa_slave_get_eee(struct net_device *dev, struct ethtool_eee *e)
 	if (ret)
 		return ret;
 
-	if (p->phy)
-		ret = phy_ethtool_get_eee(p->phy, e);
-
-	return ret;
+	return phy_ethtool_get_eee(p->phy, e);
 }
 
 #ifdef CONFIG_NET_POLL_CONTROLLER