Re: [PATCH net-next 5/5] net: dsa: mv88e6xxx: Offload bridge broadcast flooding flag

These switches have two modes of classifying broadcast:

1. Broadcast is multicast.
2. Broadcast is its own unique thing that is always flooded
   everywhere.

This driver uses the first option, making sure to load the broadcast
address into all active databases. Because of this, we can support
per-port broadcast flooding by (1) making sure to only set the subset
of ports that have it enabled whenever joining a new bridge or VLAN,
and (2) by updating all active databases whenever the setting is
changed on a port.

Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com>
---
 drivers/net/dsa/mv88e6xxx/chip.c | 68 +++++++++++++++++++++++++++++++-
 1 file changed, 67 insertions(+), 1 deletion(-)

diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
index 48e65f22641e..e6987c501fb7 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.c
+++ b/drivers/net/dsa/mv88e6xxx/chip.c

@@ -1950,6 +1950,18 @@ static int mv88e6xxx_broadcast_setup(struct mv88e6xxx_chip *chip, u16 vid)
 	int err;
 
 	for (port = 0; port < mv88e6xxx_num_ports(chip); port++) {
+		struct dsa_port *dp = dsa_to_port(chip->ds, port);
+
+		if (dsa_is_unused_port(chip->ds, port))
+			continue;
+
+		if (dsa_is_user_port(chip->ds, port) && dp->bridge_dev &&
+		    !br_port_flag_is_set(dp->slave, BR_BCAST_FLOOD))

+			/* Skip bridged user ports where broadcast
+			 * flooding is disabled.
+			 */
+			continue;
+
 		err = mv88e6xxx_port_add_broadcast(chip, port, vid);
 		if (err)
 			return err;

@@ -1958,6 +1970,51 @@ static int mv88e6xxx_broadcast_setup(struct mv88e6xxx_chip *chip, u16 vid)
 	return 0;
 }
 
+struct mv88e6xxx_port_broadcast_sync_ctx {
+	int port;
+	bool flood;
+};
+
+static int
+mv88e6xxx_port_broadcast_sync_vlan(struct mv88e6xxx_chip *chip,
+				   const struct mv88e6xxx_vtu_entry *vlan,
+				   void *_ctx)
+{
+	const char broadcast[6] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };

+	struct mv88e6xxx_port_broadcast_sync_ctx *ctx = _ctx;
+	u8 state;
+
+	if (ctx->flood)
+		state = MV88E6XXX_G1_ATU_DATA_STATE_MC_STATIC;
+	else
+		state = MV88E6XXX_G1_ATU_DATA_STATE_MC_UNUSED;
+
+	return mv88e6xxx_port_db_load_purge(chip, ctx->port, broadcast,
+					    vlan->vid, state);
+}
+
+static int mv88e6xxx_port_broadcast_sync(struct mv88e6xxx_chip *chip, int port,
+					 bool flood)
+{
+	struct mv88e6xxx_port_broadcast_sync_ctx ctx = {
+		.port = port,
+		.flood = flood,
+	};
+	struct mv88e6xxx_vtu_entry vid0 = {
+		.vid = 0,
+	};
+	int err;
+
+	/* Update the port's private database... */
+	err = mv88e6xxx_port_broadcast_sync_vlan(chip, &vid0, &ctx);
+	if (err)
+		return err;
+
+	/* ...and the database for all VLANs. */
+	return mv88e6xxx_vtu_walk(chip, mv88e6xxx_port_broadcast_sync_vlan,
+				  &ctx);
+}
+
 static int mv88e6xxx_port_vlan_join(struct mv88e6xxx_chip *chip, int port,
 				    u16 vid, u8 member, bool warn)
 {

@@ -5431,7 +5488,8 @@ static int mv88e6xxx_port_pre_bridge_flags(struct dsa_switch *ds, int port,
 	struct mv88e6xxx_chip *chip = ds->priv;
 	const struct mv88e6xxx_ops *ops;
 
-	if (flags.mask & ~(BR_LEARNING | BR_FLOOD | BR_MCAST_FLOOD))
+	if (flags.mask & ~(BR_LEARNING | BR_FLOOD | BR_MCAST_FLOOD |
+			   BR_BCAST_FLOOD))
 		return -EINVAL;
 
 	ops = chip->info->ops;

@@ -5480,6 +5538,14 @@ static int mv88e6xxx_port_bridge_flags(struct dsa_switch *ds, int port,
 			goto out;
 	}
 
+	if (flags.mask & BR_BCAST_FLOOD) {
+		bool broadcast = !!(flags.val & BR_BCAST_FLOOD);
+
+		err = mv88e6xxx_port_broadcast_sync(chip, port, broadcast);
+		if (err)
+			goto out;
+	}
+
 out:
 	mv88e6xxx_reg_unlock(chip);
 

-- 
2.25.1