target/linux/generic/pending-6.1/705-net-dsa-tag_mtk-add-padding-for-tx-packets.patch

   1 From: Felix Fietkau <nbd@nbd.name>
   2 Date: Fri, 6 May 2022 21:38:42 +0200
   3 Subject: [PATCH] net: dsa: tag_mtk: add padding for tx packets
   4
   5 Padding for transmitted packets needs to account for the special tag.
   6 With not enough padding, garbage bytes are inserted by the switch at the
   7 end of small packets.
   8
   9 Fixes: 5cd8985a1909 ("net-next: dsa: add Mediatek tag RX/TX handler")
  10 Signed-off-by: Felix Fietkau <nbd@nbd.name>
  11 ---
  12
  13 --- a/net/dsa/tag_mtk.c
  14 +++ b/net/dsa/tag_mtk.c
  15 @@ -27,6 +27,13 @@ static struct sk_buff *mtk_tag_xmit(stru
  16
  17         skb_set_queue_mapping(skb, dp->index);
  18
  19 +       /* The Ethernet switch we are interfaced with needs packets to be at
  20 +        * least 64 bytes (including FCS) otherwise their padding might be
  21 +        * corrupted. With tags enabled, we need to make sure that packets are
  22 +        * at least 68 bytes (including FCS and tag).
  23 +        */
  24 +       eth_skb_pad(skb);
  25 +
  26         /* Build the special tag after the MAC Source Address. If VLAN header
  27          * is present, it's required that VLAN header and special tag is
  28          * being combined. Only in this way we can allow the switch can parse