The current assumption is that the felix DSA driver has flooding knobs
per traffic class, while ocelot switchdev has a single flooding knob.
This was correct for felix VSC9959 and ocelot VSC7514, but with the
introduction of seville VSC9953, we see a switch driven by felix.c which
has a single flooding knob.

So it is clear that we must do what should have been done from the
beginning, which is not to overwrite the configuration done by ocelot.c
in felix, but instead to teach the common ocelot library about the
differences in our switches, and set up the flooding PGIDs centrally.

The effect that the bogus iteration through FELIX_NUM_TC has upon
seville is quite dramatic. ANA_FLOODING is located at 0x00b548, and
ANA_FLOODING_IPMC is located at 0x00b54c. So the bogus iteration will
actually overwrite ANA_FLOODING_IPMC when attempting to write
ANA_FLOODING[1]. There is no ANA_FLOODING[1] in sevile, just ANA_FLOODING.

And when ANA_FLOODING_IPMC is overwritten with a bogus value, the effect
is that ANA_FLOODING_IPMC gets the value of 0x0003CF7D:
	MC6_DATA = 61,
	MC6_CTRL = 61,
	MC4_DATA = 60,
	MC4_CTRL = 0.
Because MC4_CTRL is zero, this means that IPv4 multicast control packets
are not flooded, but dropped. An invalid configuration, and this is how
the issue was actually spotted.
Reported-by: Eldar Gasanov <eldargasanov2@gmail.com>
Reported-by: Maxim Kochetkov <fido_max@inbox.ru>
Tested-by: Eldar Gasanov <eldargasanov2@gmail.com>
Fixes: 84705fc1 ("net: dsa: felix: introduce support for Seville VSC9953 switch")
Fixes: 3c7b51bd ("net: dsa: felix: allow flooding for all traffic classes")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20201204175416.1445937-1-vladimir.oltean@nxp.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>