From: Linus Walleij linus.walleij@linaro.org
commit 86dd9868b8788a9063893a97649594af93cd5aa6 upstream.
Support also transmitting frames using the custom "8899 A" 4 byte tag.
Qingfang came up with the solution: we need to pad the ethernet frame to 60 bytes using eth_skb_pad(), then the switch will happily accept frames with custom tags.
Cc: Mauri Sandberg sandberg@mailfence.com Reported-by: DENG Qingfang dqfext@gmail.com Fixes: efd7fe68f0c6 ("net: dsa: tag_rtl4_a: Implement Realtek 4 byte A tag") Signed-off-by: Linus Walleij linus.walleij@linaro.org Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/dsa/tag_rtl4_a.c | 43 +++++++++++++++++++++++++++++-------------- 1 file changed, 29 insertions(+), 14 deletions(-)
--- a/net/dsa/tag_rtl4_a.c +++ b/net/dsa/tag_rtl4_a.c @@ -12,9 +12,7 @@ * * The 2 bytes tag form a 16 bit big endian word. The exact * meaning has been guessed from packet dumps from ingress - * frames, as no working egress traffic has been available - * we do not know the format of the egress tags or if they - * are even supported. + * frames. */
#include <linux/etherdevice.h> @@ -36,17 +34,34 @@ static struct sk_buff *rtl4a_tag_xmit(struct sk_buff *skb, struct net_device *dev) { - /* - * Just let it pass thru, we don't know if it is possible - * to tag a frame with the 0x8899 ethertype and direct it - * to a specific port, all attempts at reverse-engineering have - * ended up with the frames getting dropped. - * - * The VLAN set-up needs to restrict the frames to the right port. - * - * If you have documentation on the tagging format for RTL8366RB - * (tag type A) then please contribute. - */ + struct dsa_port *dp = dsa_slave_to_port(dev); + u8 *tag; + u16 *p; + u16 out; + + /* Pad out to at least 60 bytes */ + if (unlikely(eth_skb_pad(skb))) + return NULL; + if (skb_cow_head(skb, RTL4_A_HDR_LEN) < 0) + return NULL; + + netdev_dbg(dev, "add realtek tag to package to port %d\n", + dp->index); + skb_push(skb, RTL4_A_HDR_LEN); + + memmove(skb->data, skb->data + RTL4_A_HDR_LEN, 2 * ETH_ALEN); + tag = skb->data + 2 * ETH_ALEN; + + /* Set Ethertype */ + p = (u16 *)tag; + *p = htons(RTL4_A_ETHERTYPE); + + out = (RTL4_A_PROTOCOL_RTL8366RB << 12) | (2 << 8); + /* The lower bits is the port numer */ + out |= (u8)dp->index; + p = (u16 *)(tag + 2); + *p = htons(out); + return skb; }