[PATCH 17/20] net: dsa: xilinx: opt into TX forwarding offload on bridge join

Set *tx_fwd_offload in port_bridge_join. The bridge then sends one
copy via the offloaded TX path and the fabric handles per-port
replication.

The fabric offloads a single bridge across the user ports. Set
ds->max_num_bridges to 1 so the DSA core rejects a second bridge
instead of silently merging the ports.

Signed-off-by: Nagadheeraj Rottela <[email protected]>
---
 drivers/net/dsa/xilinx/xilinx_tsn.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/net/dsa/xilinx/xilinx_tsn.c b/drivers/net/dsa/xilinx/xilinx_tsn.c
index e48c81f18d6e..9a4d4a2fb892 100644
--- a/drivers/net/dsa/xilinx/xilinx_tsn.c
+++ b/drivers/net/dsa/xilinx/xilinx_tsn.c
@@ -495,6 +495,19 @@ static int xlnx_tsn_port_set_mac_address(struct dsa_switch *ds, int port,
 	return 0;
 }
 
+static int xlnx_tsn_port_bridge_join(struct dsa_switch *ds, int port,
+				     struct dsa_bridge bridge,
+				     bool *tx_fwd_offload,
+				     struct netlink_ext_ack *extack)
+{
+	/* The switch fabric replicates flooded frames per egress port
+	 * on its own, so the bridge does not need to clone-and-send.
+	 */
+	*tx_fwd_offload = true;
+
+	return 0;
+}
+
 static void xlnx_tsn_port_stp_state_set(struct dsa_switch *ds, int port,
 					u8 state)
 {
@@ -729,6 +742,7 @@ static const struct dsa_switch_ops xlnx_tsn_switch_ops = {
 	.setup			= xlnx_tsn_setup,
 	.teardown		= xlnx_tsn_teardown,
 	.port_set_mac_address	= xlnx_tsn_port_set_mac_address,
+	.port_bridge_join	= xlnx_tsn_port_bridge_join,
 	.port_stp_state_set	= xlnx_tsn_port_stp_state_set,
 	.port_hwtstamp_get	= xlnx_tsn_port_hwtstamp_get,
 	.port_hwtstamp_set	= xlnx_tsn_port_hwtstamp_set,
@@ -786,6 +800,9 @@ static int xlnx_tsn_probe(struct platform_device *pdev)
 	ds->phylink_mac_ops = &xlnx_tsn_phylink_mac_ops;
 	ds->priv = sw;
 
+	/* The fabric offloads a single bridge across the user ports. */
+	ds->max_num_bridges = 1;
+
 	platform_set_drvdata(pdev, sw);
 
 	return dsa_register_switch(ds);
-- 
2.34.1