[PATCH net] net: dsa: mv88e6xxx: Enable IGMP snooping on user ports only

[Fabio Estevam <festevam@gmail.com>]

From: Steffen Bätz <steffen@innosonix.de>

Do not set the MV88E6XXX_PORT_CTL0_IGMP_MLD_SNOOP bit on CPU or DSA ports.

This allows the host CPU port to be a regular IGMP listener by sending out
IGMP Membership Reports, which would otherwise not be forwarded by the
mv88exxx chip, but directly looped back to the CPU port itself.

Fixes: 54d792f257c6 ("net: dsa: Centralise global and port setup code into mv88e6xxx.")
Signed-off-by: Steffen Bätz <steffen@innosonix.de>
Signed-off-by: Fabio Estevam <festevam@denx.de>
---
Changes since RFC:
- Use dsa_is_user_port() to decide when to set the snoop bit (Andrew).
- Reword the commit message to differentiate between IGMP snooping and an IGMP listener on
the bridge.

 drivers/net/dsa/mv88e6xxx/chip.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
index b73d1d6747b7..62a126402983 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.c
+++ b/drivers/net/dsa/mv88e6xxx/chip.c
@@ -3354,9 +3354,14 @@ static int mv88e6xxx_setup_port(struct mv88e6xxx_chip *chip, int port)
 	 * If this is the upstream port for this switch, enable
 	 * forwarding of unknown unicasts and multicasts.
 	 */
-	reg = MV88E6XXX_PORT_CTL0_IGMP_MLD_SNOOP |
-		MV88E6185_PORT_CTL0_USE_TAG | MV88E6185_PORT_CTL0_USE_IP |
+	reg = MV88E6185_PORT_CTL0_USE_TAG | MV88E6185_PORT_CTL0_USE_IP |
 		MV88E6XXX_PORT_CTL0_STATE_FORWARDING;
+	/* Forward any IPv4 IGMP or IPv6 MLD frames received
+	 * by a USER port to the CPU port to allow snooping.
+	 */
+	if (dsa_is_user_port(ds, port))
+		reg |= MV88E6XXX_PORT_CTL0_IGMP_MLD_SNOOP;
+
 	err = mv88e6xxx_port_write(chip, port, MV88E6XXX_PORT_CTL0, reg);
 	if (err)
 		return err;
-- 
2.34.1