On Mon, Dec 10, 2018 at 07:56:14PM +0300, Sergei Shtylyov wrote:
> 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)?
I was hoping that others would test the patch on the same or other boards.
That is all.
>
> > 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.
It seems that David likes the #define, lets keep it.
