net: dsa: mv88e6xxx: do not flood CPU with unknown multicast

The DSA ports must flood unknown unicast and multicast, but the switch
must not flood the CPU ports with unknown multicast, as this results
in a lot of undesirable traffic that the network stack needs to filter
in software.
Signed-off-by: NVivien Didelot <vivien.didelot@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/dsa/mv88e6xxx/chip.c

@@ -2058,15 +2058,13 @@ static int mv88e6xxx_setup_message_port(struct mv88e6xxx_chip *chip, int port)
 static int mv88e6xxx_setup_egress_floods(struct mv88e6xxx_chip *chip, int port)
 {
 	struct dsa_switch *ds = chip->ds;
-	bool flood;
-
-	/* Upstream ports flood frames with unknown unicast or multicast DA */
-	flood = dsa_is_cpu_port(ds, port) || dsa_is_dsa_port(ds, port);
-	if (chip->info->ops->port_set_egress_floods)
-		return chip->info->ops->port_set_egress_floods(chip, port,
-							       flood, flood);
+	bool uc = dsa_is_dsa_port(ds, port) || dsa_is_cpu_port(ds, port);
+	bool mc = dsa_is_dsa_port(ds, port);
 
+	if (!chip->info->ops->port_set_egress_floods)
 		return 0;
+
+	return chip->info->ops->port_set_egress_floods(chip, port, uc, mc);
 }
 
 static int mv88e6xxx_serdes_power(struct mv88e6xxx_chip *chip, int port,