diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
index fc0f508879d4..b603f8d6ee3e 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.c
+++ b/drivers/net/dsa/mv88e6xxx/chip.c
@@ -2524,11 +2524,22 @@ static int mv88e6xxx_mdio_read(struct mii_bus *bus, int phy, int reg)
 	mutex_unlock(&chip->reg_lock);
 
 	if (reg == MII_PHYSID2) {
-		/* Some internal PHYS don't have a model number.  Use
-		 * the mv88e6390 family model number instead.
-		 */
-		if (!(val & 0x3f0))
-			val |= MV88E6XXX_PORT_SWITCH_ID_PROD_6390 >> 4;
+		/* Some internal PHYs don't have a model number. */
+		if (chip->info->family != MV88E6XXX_FAMILY_6165)
+			/* Then there is the 6165 family. It gets is
+			 * PHYs correct. But it can also have two
+			 * SERDES interfaces in the PHY address
+			 * space. And these don't have a model
+			 * number. But they are not PHYs, so we don't
+			 * want to give them something a PHY driver
+			 * will recognise.
+			 *
+			 * Use the mv88e6390 family model number
+			 * instead, for anything which really could be
+			 * a PHY,
+			 */
+			if (!(val & 0x3f0))
+				val |= MV88E6XXX_PORT_SWITCH_ID_PROD_6390 >> 4;
 	}
 
 	return err ? err : val;