diff --git a/drivers/net/dsa/microchip/ksz9477.c b/drivers/net/dsa/microchip/ksz9477.c
index 602d00671bef..f6e7968ab105 100644
--- a/drivers/net/dsa/microchip/ksz9477.c
+++ b/drivers/net/dsa/microchip/ksz9477.c
@@ -45,19 +45,15 @@ static void ksz9477_port_cfg32(struct ksz_device *dev, int port, int offset,
 
 int ksz9477_change_mtu(struct ksz_device *dev, int port, int mtu)
 {
-	u16 frame_size, max_frame = 0;
-	int i;
+	u16 frame_size;
+
+	if (!dsa_is_cpu_port(dev->ds, port))
+		return 0;
 
 	frame_size = mtu + VLAN_ETH_HLEN + ETH_FCS_LEN;
 
-	/* Cache the per-port MTU setting */
-	dev->ports[port].max_frame = frame_size;
-
-	for (i = 0; i < dev->info->port_cnt; i++)
-		max_frame = max(max_frame, dev->ports[i].max_frame);
-
 	return regmap_update_bits(dev->regmap[1], REG_SW_MTU__2,
-				  REG_SW_MTU_MASK, max_frame);
+				  REG_SW_MTU_MASK, frame_size);
 }
 
 static int ksz9477_wait_vlan_ctrl_ready(struct ksz_device *dev)
diff --git a/drivers/net/dsa/microchip/ksz_common.h b/drivers/net/dsa/microchip/ksz_common.h
index 27c26ee15af4..61228be299f9 100644
--- a/drivers/net/dsa/microchip/ksz_common.h
+++ b/drivers/net/dsa/microchip/ksz_common.h
@@ -95,7 +95,6 @@ struct ksz_port {
 
 	struct ksz_port_mib mib;
 	phy_interface_t interface;
-	u16 max_frame;
 	u32 rgmii_tx_val;
 	u32 rgmii_rx_val;
 	struct ksz_device *ksz_dev;