[PATCH v2] net/i40e: restore disable double VLAN by default

[Kevin Liu <kevinx.liu@intel.com>]

Previously, QinQ was enabled by default and cannot be disable,
But a serious issue was found during the performance test,
if QinQ is always enable, the performance will drop seriously.

So, restore disable double VLAN by default and eliminate the
impact of QinQ on Performance.

doc: update known issue.

Fixes: ae97b8b89826 ("net/i40e: fix error disable double VLAN")
Signed-off-by: Kevin Liu <kevinx.liu@intel.com>

---
v2: update doc and refine commit log
---
 doc/guides/nics/i40e.rst       | 11 +++++++----
 drivers/net/i40e/i40e_ethdev.c | 12 ------------
 2 files changed, 7 insertions(+), 16 deletions(-)

diff --git a/doc/guides/nics/i40e.rst b/doc/guides/nics/i40e.rst
index 85fdc4944d..75ff40aa59 100644
--- a/doc/guides/nics/i40e.rst
+++ b/doc/guides/nics/i40e.rst
@@ -969,11 +969,14 @@ it will fail and return the info "Conflict with the first rule's input set",
 which means the current rule's input set conflicts with the first rule's.
 Remove the first rule if want to change the input set of the PCTYPE.
 
-Disable QinQ is not supported when FW >= 8.4
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-If upgrade FW to version 8.4 and higher, enable QinQ by default and disable QinQ is not supported.
+Vlan related feature miss when FW >= 8.4
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
+If upgrade FW to version 8.4 and higher, some vlan related issue exist:
+1. vlan tci input set not work
+2. tpid set fail
+3. need enable qinq before use vlan filter
+4. outer vlan strip fail
 
 Example of getting best performance with l3fwd example
 ------------------------------------------------------
diff --git a/drivers/net/i40e/i40e_ethdev.c b/drivers/net/i40e/i40e_ethdev.c
index 684e095026..117dd85c11 100644
--- a/drivers/net/i40e/i40e_ethdev.c
+++ b/drivers/net/i40e/i40e_ethdev.c
@@ -4027,12 +4027,6 @@ i40e_vlan_offload_set(struct rte_eth_dev *dev, int mask)
 	}
 
 	if (mask & RTE_ETH_VLAN_EXTEND_MASK) {
-		/* Double VLAN not allowed to be disabled.*/
-		if (pf->fw8_3gt && !(rxmode->offloads & RTE_ETH_RX_OFFLOAD_VLAN_EXTEND)) {
-			PMD_DRV_LOG(WARNING,
-				"Disable double VLAN is not allowed after firmwarev8.3!");
-			return 0;
-		}
 		i = 0;
 		num = vsi->mac_num;
 		mac_filter = rte_zmalloc("mac_filter_info_data",
@@ -6296,7 +6290,6 @@ int i40e_vsi_cfg_inner_vlan_stripping(struct i40e_vsi *vsi, bool on)
 static int
 i40e_dev_init_vlan(struct rte_eth_dev *dev)
 {
-	struct i40e_pf *pf = I40E_DEV_PRIVATE_TO_PF(dev->data->dev_private);
 	struct rte_eth_dev_data *data = dev->data;
 	int ret;
 	int mask = 0;
@@ -6307,11 +6300,6 @@ i40e_dev_init_vlan(struct rte_eth_dev *dev)
 	       RTE_ETH_VLAN_FILTER_MASK |
 	       RTE_ETH_VLAN_EXTEND_MASK;
 
-	/* Double VLAN be enabled by default.*/
-	if (pf->fw8_3gt) {
-		struct rte_eth_rxmode *rxmode = &dev->data->dev_conf.rxmode;
-		rxmode->offloads |= RTE_ETH_RX_OFFLOAD_VLAN_EXTEND;
-	}
 	ret = i40e_vlan_offload_set(dev, mask);
 	if (ret) {
 		PMD_DRV_LOG(INFO, "Failed to update vlan offload");
-- 
2.34.1