mv643xx_eth: fix unicast filter programming in promiscuous mode

The Unicast Promiscious Mode (UPM) bit in the mv643xx_eth port
configuration register doesn't do exactly what its name would suggest:
setting this bit merely enables reception of all unicast frames with a
destination address that differs from our local MAC address in bits
[47:4].  In particular, it doesn't have any effect on unicast frames
with a destination address that matches our MAC address in bits [47:4]
-- these will still be tested against the 16-entry unicast address
filter table.

Therefore, if the interface is set to promiscuous mode, just setting
the unicast promiscuous bit isn't enough -- we need to set all filter
bits in the unicast filter table to 1 as well.
Reported-by: NSachin Sanap <ssanap@marvell.com>
Signed-off-by: NPrabhanjan Sarnaik <sarnaik@marvell.com>
Tested-by: NSiddarth Gore <gores@marvell.com>
Tested-by: NMahavir Jain <mjain@marvell.com>
Signed-off-by: NLennert Buytenhek <buytenh@marvell.com>
Cc: stable@kernel.org
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/mv643xx_eth.c

@@ -1750,12 +1750,12 @@ static void mv643xx_eth_program_unicast_filter(struct net_device *dev)
 
 	uc_addr_set(mp, dev->dev_addr);
 
-	port_config = rdlp(mp, PORT_CONFIG);
+	port_config = rdlp(mp, PORT_CONFIG) & ~UNICAST_PROMISCUOUS_MODE;
+
 	nibbles = uc_addr_filter_mask(dev);
 	if (!nibbles) {
 		port_config |= UNICAST_PROMISCUOUS_MODE;
-		wrlp(mp, PORT_CONFIG, port_config);
-		return;
+		nibbles = 0xffff;
 	}
 
 	for (i = 0; i < 16; i += 4) {
@@ -1776,7 +1776,6 @@ static void mv643xx_eth_program_unicast_filter(struct net_device *dev)
 		wrl(mp, off, v);
 	}
 
-	port_config &= ~UNICAST_PROMISCUOUS_MODE;
 	wrlp(mp, PORT_CONFIG, port_config);
 }