net/e1000: fix max Rx packet size

[ upstream commit ddbc8c1 ]

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: e51abef ("igb: fix max RX packet size and support dual VLAN")

Signed-off-by: Alvin Zhang <alvinx.zhang@intel.com>
Tested-by: Lingli Chen <linglix.chen@intel.com>
Acked-by: Haiyue Wang <haiyue.wang@intel.com>

drivers/net/e1000/igb_ethdev.c

@@ -2710,8 +2710,7 @@ igb_vlan_hw_extend_disable(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
@@ -2730,7 +2729,7 @@ igb_vlan_hw_extend_enable(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

drivers/net/e1000/igb_rxtx.c

@@ -2341,15 +2341,18 @@ eth_igb_rx_init(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;