[dpdk-dev] [PATCH v4 2/5] net/igc: fix max mtu size packets with vlan tag cannot be received by default

[SteveX Yang]

testpmd will initialize default max packet length to 1518 which doesn't
include vlan tag size in ether overheader. Once, send the max mtu length
packet with vlan tag, the max packet length will exceed 1518 that will
cause packets dropped directly from NIC hw side.

igc can support single vlan tag that need more 4 bytes for max packet size,
so, configures the correct max packet size in dev_config ops.

Fixes: a5aeb2b9e225 ("net/igc: support Rx and Tx")

Signed-off-by: SteveX Yang <stevex.yang at intel.com>
---
 drivers/net/igc/igc_ethdev.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/net/igc/igc_ethdev.c b/drivers/net/igc/igc_ethdev.c
index 810568bc5..f47ea3e64 100644
--- a/drivers/net/igc/igc_ethdev.c
+++ b/drivers/net/igc/igc_ethdev.c
@@ -337,11 +337,22 @@ static int
 eth_igc_configure(struct rte_eth_dev *dev)
 {
 	struct igc_interrupt *intr = IGC_DEV_PRIVATE_INTR(dev);
+	uint32_t frame_size = dev->data->mtu + IGC_ETH_OVERHEAD;
 	int ret;
 
 	PMD_INIT_FUNC_TRACE();
 
-	ret  = igc_check_mq_mode(dev);
+	/**
+	 * Considering vlan tag packet, max frame size should be equal or
+	 * larger than total size of MTU and Ether overhead.
+	 */
+	if (frame_size > dev->data->dev_conf.rxmode.max_rx_pkt_len) {
+		ret = eth_igc_mtu_set(dev, dev->data->mtu);
+		if (ret != 0)
+			return ret;
+	}
+
+	ret = igc_check_mq_mode(dev);
 	if (ret != 0)
 		return ret;
 
-- 
2.17.1