+/* The Cisco NIC can send and receive packets up to a max packet size
+ * determined by the NIC type and firmware. There is also an MTU
+ * configured into the NIC via the CIMC/UCSM management interface
+ * which can be overridden by this function (up to the max packet size).
+ * Depending on the network setup, doing so may cause packet drops
+ * and unexpected behavior.
+ */
+int enic_set_mtu(struct enic *enic, uint16_t new_mtu)
+{
+ uint16_t old_mtu; /* previous setting */
+ uint16_t config_mtu; /* Value configured into NIC via CIMC/UCSM */
+ struct rte_eth_dev *eth_dev = enic->rte_dev;
+
+ old_mtu = eth_dev->data->mtu;
+ config_mtu = enic->config.mtu;
+
+ /* only works with Rx scatter disabled */
+ if (enic->rte_dev->data->dev_conf.rxmode.enable_scatter)
+ return -ENOTSUP;
+
+ if (new_mtu > enic->max_mtu) {
+ dev_err(enic,
+ "MTU not updated: requested (%u) greater than max (%u)\n",
+ new_mtu, enic->max_mtu);
+ return -EINVAL;
+ }
+ if (new_mtu < ENIC_MIN_MTU) {
+ dev_info(enic,
+ "MTU not updated: requested (%u) less than min (%u)\n",
+ new_mtu, ENIC_MIN_MTU);
+ return -EINVAL;
+ }
+ if (new_mtu > config_mtu)
+ dev_warning(enic,
+ "MTU (%u) is greater than value configured in NIC (%u)\n",
+ new_mtu, config_mtu);
+
+ /* update the mtu */
+ eth_dev->data->mtu = new_mtu;
+
+ dev_info(enic, "MTU changed from %u to %u\n", old_mtu, new_mtu);
+ return 0;
+}
+