net: bcmgenet: properly disable password matching

bcmgenet_set_wol() correctly sets MPD_PW_EN when a password is specified
to match magic packets against, however, when we switch from a
password-matching to a matching without password we would leave this bit
turned on, and GENET would only match magic packets with passwords.

This can be reproduced using the following sequence:

ethtool -s eth0 wol g
ethtool -s eth0 wol s sopass 00:11:22:33:44:55
ethtool -s eth0 wol g

The simple fix is to clear the MPD_PWD_EN bit when WAKE_MAGICSECURE is
not set.

Fixes: c51de7f3976b ("net: bcmgenet: add Wake-on-LAN support code")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/genet/bcmgenet_wol.c

@@ -73,15 +73,17 @@ int bcmgenet_set_wol(struct net_device *dev, struct ethtool_wolinfo *wol)
 	if (wol->wolopts & ~(WAKE_MAGIC | WAKE_MAGICSECURE))
 		return -EINVAL;
 
+	reg = bcmgenet_umac_readl(priv, UMAC_MPD_CTRL);
 	if (wol->wolopts & WAKE_MAGICSECURE) {
 		bcmgenet_umac_writel(priv, get_unaligned_be16(&wol->sopass[0]),
 				     UMAC_MPD_PW_MS);
 		bcmgenet_umac_writel(priv, get_unaligned_be32(&wol->sopass[2]),
 				     UMAC_MPD_PW_LS);
-		reg = bcmgenet_umac_readl(priv, UMAC_MPD_CTRL);
 		reg |= MPD_PW_EN;
-		bcmgenet_umac_writel(priv, reg, UMAC_MPD_CTRL);
+	} else {
+		reg &= ~MPD_PW_EN;
 	}
+	bcmgenet_umac_writel(priv, reg, UMAC_MPD_CTRL);
 
 	/* Flag the device and relevant IRQ as wakeup capable */
 	if (wol->wolopts) {