Since the driver does not act upon the max_sdu argument, deny any other
values except the default all-zeroes, which means that all traffic
classes should use the same MTU as the port itself.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
 drivers/net/ethernet/intel/igc/igc_main.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index bf6c461e1a2a..47fae443066c 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -5965,11 +5965,15 @@ static int igc_tsn_enable_qbv_scheduling(struct igc_adapter *adapter,
 					 struct tc_taprio_qopt_offload *qopt)
 {
 	struct igc_hw *hw = &adapter->hw;
-	int err;
+	int tc, err;
 
 	if (hw->mac.type != igc_i225)
 		return -EOPNOTSUPP;
 
+	for (tc = 0; tc < TC_MAX_QUEUE; tc++)
+		if (qopt->max_sdu[tc])
+			return -EOPNOTSUPP;
+
 	err = igc_save_qbv_schedule(adapter, qopt);
 	if (err)
 		return err;
-- 
2.34.1