From 19a1808003af3e87f903a053b2207a59f6bb3456 Mon Sep 17 00:00:00 2001
From: Ajit Khaparde <ajit.khaparde@broadcom.com>
Date: Thu, 28 Jun 2018 13:15:43 -0700
Subject: [PATCH] net/bnxt: fix set MTU

There is no need to update bnxt_hwrm_vnic_plcmode_cfg if new MTU is
not greater than the max data the mbuf can accommodate.

Fixes: daef48efe5e5 ("net/bnxt: support set MTU")
Cc: stable@dpdk.org

Signed-off-by: Ajit Khaparde <ajit.khaparde@broadcom.com>
(cherry picked from commit 42e4af421e80ee4a07730a83fd9a7a6b9a1fbe26)
---
 drivers/net/bnxt/bnxt_ethdev.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/net/bnxt/bnxt_ethdev.c b/drivers/net/bnxt/bnxt_ethdev.c
index 9a6209d6c..775b99cab 100644
--- a/drivers/net/bnxt/bnxt_ethdev.c
+++ b/drivers/net/bnxt/bnxt_ethdev.c
@@ -1537,6 +1537,7 @@ static int bnxt_mtu_set_op(struct rte_eth_dev *eth_dev, uint16_t new_mtu)
 
 	for (i = 0; i < bp->nr_vnics; i++) {
 		struct bnxt_vnic_info *vnic = &bp->vnic_info[i];
+		uint16_t size = 0;
 
 		vnic->mru = bp->eth_dev->data->mtu + ETHER_HDR_LEN +
 					ETHER_CRC_LEN + VLAN_TAG_SIZE * 2;
@@ -1544,9 +1545,14 @@ static int bnxt_mtu_set_op(struct rte_eth_dev *eth_dev, uint16_t new_mtu)
 		if (rc)
 			break;
 
-		rc = bnxt_hwrm_vnic_plcmode_cfg(bp, vnic);
-		if (rc)
-			return rc;
+		size = rte_pktmbuf_data_room_size(bp->rx_queues[0]->mb_pool);
+		size -= RTE_PKTMBUF_HEADROOM;
+
+		if (size < new_mtu) {
+			rc = bnxt_hwrm_vnic_plcmode_cfg(bp, vnic);
+			if (rc)
+				return rc;
+		}
 	}
 
 	return rc;
-- 
2.17.1