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With this patch we try to kill 2 birds with 1 stone. First of all, some switches that use tag_ocelot.c don't have the exact same bitfield layout for the DSA tags. The destination ports field is different for Seville VSC9953 for example. So the choices are to either duplicate tag_ocelot.c into a new tag_seville.c (sub-optimal) or somehow take into account a supposed ocelot->dest_ports_offset when packing this field into the DSA injection header (again not ideal). Secondly, tag_ocelot.c already needs to memset a 128-bit area to zero and call some packing() functions of dubious performance in the fastpath. And most of the values it needs to pack are pretty much constant (BYPASS=1, SRC_PORT=CPU, DEST=port index). So it would be good if we could improve that. The proposed solution is to allocate a memory area per port at probe time, initialize that with the statically defined bits as per chip hardware revision, and just perform a simpler memcpy in the fastpath. Other alternatives have been analyzed, such as: - Create a separate tag_seville.c: too much code duplication for just 1 bit field difference. - Create a separate DSA_TAG_PROTO_SEVILLE under tag_ocelot.c, just like tag_brcm.c, which would have a separate .xmit function. Again, too much code duplication for just 1 bit field difference. - Allocate the template from the init function of the tag_ocelot.c module, instead of from the driver: couldn't figure out a method of accessing the correct port template corresponding to the correct tagger in the .xmit function. 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.