VLAN not working with eth_nxp_enet driver

[anhuba]

When switching from v3.6 to v3.7 we realized that VLAN is not working on our SOC_MIMXRT1064 board anymore. After analyzing the problem we found out the problem is the default setting of the new nxp_enet driver (with the eth_mcux in v3.6 it worked fine)

The new driver has the HW acceleration (ETH_NXP_ENET_HW_ACCELERATION) enabled by default. If using CONFIG_NET_VLAN the checksums for IP, TCP/UDP are calculated in SW as the VLAN interface does not use the information from the lower interface. The HW then calculates the checksums with non-zeroed values which results in checksum with the value 0xffff instead of the correct value.

If CONFIG_ETH_NXP_ENET_HW_ACCELERATION is disabled in the config and everything calculated in SW it works fine.

To make use of the HW acceleration and VLAN at the same time, I have added the following lines, which work fine in our setup:

--- A/zephyr/subsys/net/ip/net_if.c 2024-10-01 13:31:51.000000000 
+++ B/zephyr/subsys/net/ip/net_if.c 2024-10-01 11:02:28.000000000 
@@ -5169,12 +5169,16 @@
                  enum net_if_checksum_type chksum_type)
 {
 #if defined(CONFIG_NET_L2_ETHERNET)
    struct ethernet_config config;
    enum ethernet_config_type config_type;

+   if (IS_ENABLED(CONFIG_NET_VLAN) && net_eth_is_vlan_interface(iface)) {
+       iface = net_eth_get_vlan_main(iface);
+   }
+
    if (net_if_l2(iface) != &NET_L2_GET_NAME(ETHERNET)) {
        /* For VLANs, figure out the main Ethernet interface and
         * get the offloading capabilities from it.
         */
        if (IS_ENABLED(CONFIG_NET_VLAN) && net_eth_is_vlan_interface(iface)) {
            iface = net_eth_get_vlan_main(iface);

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[jukkar]

This should be fixed by this https://github.com/zephyrproject-rtos/zephyr/pull/78745

[jukkar]

You seem to have the fix according to your code example.

[anhuba]

oops did not find the fix... already fixed in 00bb90a42e7f583704090c5e38e1b3fd933cf409