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In VLAN-unaware mode, sja1105 uses VLAN tags with a custom TPID of 0xdadb. While in the yet-to-be introduced best_effort_vlan_filtering mode, it needs to work with normal VLAN TPID values. A complication arises when we must transmit a VLAN-tagged packet to the switch when it's in VLAN-aware mode. We need to construct a packet with 2 VLAN tags, and the switch will use the outer header for routing and pop it on egress. But sadly, here the 2 hardware generations don't behave the same: - E/T switches won't pop an ETH_P_8021AD tag on egress, it seems (packets will remain double-tagged). - P/Q/R/S switches will drop a packet with 2 ETH_P_8021Q tags (it looks like it tries to prevent VLAN hopping). But looks like the reverse is also true: - E/T switches have no problem popping the outer tag from packets with 2 ETH_P_8021Q tags. - P/Q/R/S will have no problem popping a single tag even if that is ETH_P_8021AD. So it is clear that if we want the hardware to work with dsa_8021q tagging in VLAN-aware mode, we need to send different TPIDs depending on revision. Keep that information in priv->info->qinq_tpid. The per-port tagger structure will hold an xmit_tpid value that depends not only upon the qinq_tpid, but also upon the VLAN awareness state itself (in case we must transmit using 0xdadb). Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.