[dpdk-stable] [PATCH v2] net/e1000: fix max Rx packet size

[Alvin Zhang <alvinx.zhang@intel.com>]

According to E1000_ETH_OVERHEAD definition, max_rx_pkt_len contains
one VLAN tag size. Therefore when config RLPML register, if dual VLAN
not enabled there is no need to add VLAN tag size to max_rx_pkt_len,
otherwise only one another VLAN tag size should be added to.

Fixes: e51abef39382 ("igb: fix max RX packet size and support dual VLAN")
Cc: stable@dpdk.org

Signed-off-by: Alvin Zhang <alvinx.zhang@intel.com>
---

V2: Update commit log
---
 drivers/net/e1000/igb_ethdev.c | 5 ++---
 drivers/net/e1000/igb_rxtx.c   | 9 ++++++---
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/net/e1000/igb_ethdev.c b/drivers/net/e1000/igb_ethdev.c
index 2927cd7..7df7b0f 100644
--- a/drivers/net/e1000/igb_ethdev.c
+++ b/drivers/net/e1000/igb_ethdev.c
@@ -2688,8 +2688,7 @@ static int eth_igbvf_xstats_get_names(__rte_unused struct rte_eth_dev *dev,
 	/* Update maximum packet length */
 	if (dev->data->dev_conf.rxmode.offloads & DEV_RX_OFFLOAD_JUMBO_FRAME)
 		E1000_WRITE_REG(hw, E1000_RLPML,
-			dev->data->dev_conf.rxmode.max_rx_pkt_len +
-						VLAN_TAG_SIZE);
+				dev->data->dev_conf.rxmode.max_rx_pkt_len);
 }
 
 static void
@@ -2708,7 +2707,7 @@ static int eth_igbvf_xstats_get_names(__rte_unused struct rte_eth_dev *dev,
 	if (dev->data->dev_conf.rxmode.offloads & DEV_RX_OFFLOAD_JUMBO_FRAME)
 		E1000_WRITE_REG(hw, E1000_RLPML,
 			dev->data->dev_conf.rxmode.max_rx_pkt_len +
-						2 * VLAN_TAG_SIZE);
+						VLAN_TAG_SIZE);
 }
 
 static int
diff --git a/drivers/net/e1000/igb_rxtx.c b/drivers/net/e1000/igb_rxtx.c
index 1500d2f..81f06f9 100644
--- a/drivers/net/e1000/igb_rxtx.c
+++ b/drivers/net/e1000/igb_rxtx.c
@@ -2343,15 +2343,18 @@ int eth_igb_rss_hash_conf_get(struct rte_eth_dev *dev,
 	 * Configure support of jumbo frames, if any.
 	 */
 	if (dev->data->dev_conf.rxmode.offloads & DEV_RX_OFFLOAD_JUMBO_FRAME) {
+		uint32_t max_len = dev->data->dev_conf.rxmode.max_rx_pkt_len;
+
 		rctl |= E1000_RCTL_LPE;
 
 		/*
 		 * Set maximum packet length by default, and might be updated
 		 * together with enabling/disabling dual VLAN.
 		 */
-		E1000_WRITE_REG(hw, E1000_RLPML,
-			dev->data->dev_conf.rxmode.max_rx_pkt_len +
-						VLAN_TAG_SIZE);
+		if (rxmode->offloads & DEV_RX_OFFLOAD_VLAN_EXTEND)
+			max_len += VLAN_TAG_SIZE;
+
+		E1000_WRITE_REG(hw, E1000_RLPML, max_len);
 	} else
 		rctl &= ~E1000_RCTL_LPE;
 
-- 
1.8.3.1