diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c b/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c
index a42035cec611c3b141585103735a171472bd09c8..c235edd2b182a387eb7cb4c53b2bfaa21db39cf2 100644
--- a/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c
+++ b/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c
@@ -668,12 +668,14 @@ static int lan966x_fdma_get_max_mtu(struct lan966x *lan966x)
 	int i;
 
 	for (i = 0; i < lan966x->num_phys_ports; ++i) {
+		struct lan966x_port *port;
 		int mtu;
 
-		if (!lan966x->ports[i])
+		port = lan966x->ports[i];
+		if (!port)
 			continue;
 
-		mtu = lan966x->ports[i]->dev->mtu;
+		mtu = lan_rd(lan966x, DEV_MAC_MAXLEN_CFG(port->chip_port));
 		if (mtu > max_mtu)
 			max_mtu = mtu;
 	}
@@ -733,6 +735,8 @@ int lan966x_fdma_change_mtu(struct lan966x *lan966x)
 
 	max_mtu = lan966x_fdma_get_max_mtu(lan966x);
 	max_mtu += IFH_LEN * sizeof(u32);
+	max_mtu += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
+	max_mtu += VLAN_HLEN * 2;
 
 	if (round_up(max_mtu, PAGE_SIZE) / PAGE_SIZE - 1 ==
 	    lan966x->rx.page_order)
diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_main.c b/drivers/net/ethernet/microchip/lan966x/lan966x_main.c
index b3070c3fcad0a2ce1b9dce4ae72ac9921583847f..20ee5b28f70a5c59f1024d5ec53409d13588315a 100644
--- a/drivers/net/ethernet/microchip/lan966x/lan966x_main.c
+++ b/drivers/net/ethernet/microchip/lan966x/lan966x_main.c
@@ -395,7 +395,7 @@ static int lan966x_port_change_mtu(struct net_device *dev, int new_mtu)
 
 	err = lan966x_fdma_change_mtu(lan966x);
 	if (err) {
-		lan_wr(DEV_MAC_MAXLEN_CFG_MAX_LEN_SET(old_mtu),
+		lan_wr(DEV_MAC_MAXLEN_CFG_MAX_LEN_SET(LAN966X_HW_MTU(old_mtu)),
 		       lan966x, DEV_MAC_MAXLEN_CFG(port->chip_port));
 		dev->mtu = old_mtu;
 	}