net: dsa: tag_ksz: dont let the hardware process the layer 4 checksum
requested to merge github/fork/linosanfilippo-kunbus/fix/REVPI-1378/fix_wrong_checksum into devel/revpi-5.10
Created by: linosanfilippo-kunbus
If the checksum calculation is offloaded to the network device (e.g due to NETIF_F_HW_CSUM inherited from the DSA master device), the calculated layer 4 checksum is incorrect. This is since the DSA tag which is placed after the layer 4 data is considered as being part of the daa and thus errorneously included into the checksum calculation. To avoid this, always calculate the layer 4 checksum in software.
TODO: check if upstream solution is available and use that instead of this patch
Signed-off-by: Lino Sanfilippo l.sanfilippo@kunbus.com