From: Simon Horman <horms+renesas@xxxxxxxxxxxx>
Date: Wed, 23 Jan 2019 12:14:52 +0100
> EtherAVB may provide a checksum of packet data appended to packet data. In
> order to allow this checksum to be received by the host descriptor data
> needs to be enlarged by 2 bytes to accommodate the checksum.
>
> In the case of MTU-sized packets without a VLAN tag the
> checksum were already accommodated by virtue of the space reserved for the
> VLAN tag. However, a packet of MTU-size with a VLAN tag consumed all
> packet data space provided by a descriptor leaving no space for the
> trailing checksum.
>
> This was not detected by the driver which incorrectly used the last two
> bytes of packet data as the checksum and truncate the packet by two bytes.
> This resulted all such packets being dropped.
>
> A work around is to disable RX checksum offload
> # ethtool -K eth0 rx off
>
> This patch resolves this problem by increasing the size available for
> packet data in RX descriptors by two bytes.
>
> Tested on R-Car E3 (r8a77990) ES1.0 based Ebisu-4D board
>
> v2
> * Use sizeof(__sum16) directly rather than adding a driver-local
> #define for the size of the checksum provided by the hw (2 bytes).
>
> Fixes: 4d86d3818627 ("ravb: RX checksum offload")
> Signed-off-by: Simon Horman <horms+renesas@xxxxxxxxxxxx>
Applied and queued up for -stable.
