Hello!
On 12/10/2018 11:59 AM, Simon Horman wrote:
> From: Simon Horman <horms@xxxxxxxxxxxx>
>
> 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. It also introduces
> RAVB_CSUM_LEN to make things a little clearer than "2" sprinkled lightly
> over the driver.
I think a comment would work better in this case.
> Tested on R-Car E3 (r8a77990) ES1.0 based Ebisu-4D board
You need more testing (RFT specified in the subject)?
> Fixes: 4d86d3818627 ("ravb: RX checksum offload")
> Signed-off-by: Simon Horman <horms+renesas@xxxxxxxxxxxx>
> ---
> drivers/net/ethernet/renesas/ravb_main.c | 14 +++++++++-----
> 1 file changed, 9 insertions(+), 5 deletions(-)
>
> I have marked this patch as RTF as I would like it to see further testing
> before being applied.
>
> diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
> index defed0d0c51d..f7f130cf61e4 100644
> --- a/drivers/net/ethernet/renesas/ravb_main.c
> +++ b/drivers/net/ethernet/renesas/ravb_main.c
> @@ -40,6 +40,8 @@
> NETIF_MSG_RX_ERR | \
> NETIF_MSG_TX_ERR)
>
> +#define RAVB_CSUM_LEN 2
What's EtherAVB specific there, why RAVB prefix?
[...]
> @@ -350,7 +352,7 @@ static int ravb_ring_init(struct net_device *ndev, int q)
> int i;
>
> priv->rx_buf_sz = (ndev->mtu <= 1492 ? PKT_BUF_SZ : ndev->mtu) +
> - ETH_HLEN + VLAN_HLEN;
> + ETH_HLEN + VLAN_HLEN + RAVB_CSUM_LEN;
This is a fix per se. Let's add the #define (if we really need it) in
another patch.
[...]
MBR, Sergei
