net: phy: don't allow __set_phy_supported to add unsupported modes

Currently __set_phy_supported allows to add modes w/o checking whether
the PHY supports them. This is wrong, it should never add modes but
only remove modes we don't want to support.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/phy_device.c

@@ -1898,37 +1898,23 @@ EXPORT_SYMBOL(genphy_loopback);
 
 static int __set_phy_supported(struct phy_device *phydev, u32 max_speed)
 {
-	__ETHTOOL_DECLARE_LINK_MODE_MASK(speeds) = { 0, };
-
-	linkmode_set_bit_array(phy_10_100_features_array,
-			       ARRAY_SIZE(phy_10_100_features_array),
-			       speeds);
-	linkmode_set_bit_array(phy_gbit_features_array,
-			       ARRAY_SIZE(phy_gbit_features_array),
-			       speeds);
-
-	linkmode_andnot(phydev->supported, phydev->supported, speeds);
-
 	switch (max_speed) {
-	default:
-		return -ENOTSUPP;
-	case SPEED_1000:
-		linkmode_set_bit(ETHTOOL_LINK_MODE_1000baseT_Half_BIT,
-				 phydev->supported);
-		linkmode_set_bit(ETHTOOL_LINK_MODE_1000baseT_Full_BIT,
-				 phydev->supported);
+	case SPEED_10:
+		linkmode_clear_bit(ETHTOOL_LINK_MODE_100baseT_Half_BIT,
+				   phydev->supported);
+		linkmode_clear_bit(ETHTOOL_LINK_MODE_100baseT_Full_BIT,
+				   phydev->supported);
 		/* fall through */
 	case SPEED_100:
-		linkmode_set_bit(ETHTOOL_LINK_MODE_100baseT_Half_BIT,
-				 phydev->supported);
-		linkmode_set_bit(ETHTOOL_LINK_MODE_100baseT_Full_BIT,
-				 phydev->supported);
-		/* fall through */
-	case SPEED_10:
-		linkmode_set_bit(ETHTOOL_LINK_MODE_10baseT_Half_BIT,
-				 phydev->supported);
-		linkmode_set_bit(ETHTOOL_LINK_MODE_10baseT_Full_BIT,
-				 phydev->supported);
+		linkmode_clear_bit(ETHTOOL_LINK_MODE_1000baseT_Half_BIT,
+				   phydev->supported);
+		linkmode_clear_bit(ETHTOOL_LINK_MODE_1000baseT_Full_BIT,
+				   phydev->supported);
+		break;
+	case SPEED_1000:
+		break;
+	default:
+		return -ENOTSUPP;
 	}
 
 	return 0;