On 7/7/2020 2:16 PM, Linus Walleij wrote:
> This implements the known parts of the Realtek 4 byte
> tag protocol version 0xA, as found in the RTL8366RB
> DSA switch.
>
> It is designated as protocol version 0xA as a
> different Realtek 4 byte tag format with protocol
> version 0x9 is known to exist in the Realtek RTL8306
> chips.
>
> The tag and switch chip lacks public documentation, so
> the tag format has been reverse-engineered from
> packet dumps. As only ingress traffic has been available
> for analysis an egress tag has not been possible to
> develop (even using educated guesses about bit fields)
> so this is as far as it gets. It is not known if the
> switch even supports egress tagging.
>
> Excessive attempts to figure out the egress tag format
> was made. When nothing else worked, I just tried all bit
> combinations with 0xannp where a is protocol and p is
> port. I looped through all values several times trying
> to get a response from ping, without any positive
> result.
>
> Using just these ingress tags however, the switch
> functionality is vastly improved and the packets find
> their way into the destination port without any
> tricky VLAN configuration. On the D-Link DIR-685 the
> LAN ports now come up and respond to ping without
> any command line configuration so this is a real
> improvement for users.
>
> Egress packets need to be restricted to the proper
> target ports using VLAN, which the RTL8366RB DSA
> switch driver already sets up.
>
> Cc: DENG Qingfang <dqf...@gmail.com>
> Cc: Mauri Sandberg <sandb...@mailfence.com>
> Reviewed-by: Andrew Lunn <and...@lunn.ch>
> Signed-off-by: Linus Walleij <linus.wall...@linaro.org>
[snip]
> + * -------------------------------------------------
> + * | MAC DA | MAC SA | 0x8899 | 2 bytes tag | Type |
> + * -------------------------------------------------
> + *
> + * The 2 bytes tag form a 16 bit big endian word. The exact
> + * meaning has been guess from packet dumps from ingress
s/guess/guessed/
[snip]
> + port = protport & 0xff;
> +
> + /* Remove RTL4 tag and recalculate checksum */
> + skb_pull_rcsum(skb, RTL4_A_HDR_LEN);
> +
> + /* Move ethernet DA and SA in front of the data */
> + memmove(skb->data - ETH_HLEN,
> + skb->data - ETH_HLEN - RTL4_A_HDR_LEN,
> + 2 * ETH_ALEN);
> +
> + skb->dev = dsa_master_find_slave(dev, 0, port);
You would want to do this prior to doing the skb_pull_rcsum() and
memmove(), if the port is invalid, no point in pulling the SKB.
With those fixed:
Reviewed-by: Florian Fainelli <f.faine...@gmail.com>
--
Florian
