On Wed, Feb 28, 2024 at 08:05:16PM -0800, Jakub Kicinski wrote:

On Wed, 28 Feb 2024 11:13:23 +0000 Sanjuán García, Jorge wrote:

quoted

Since commit 8940e6b669ca ("net: dsa: avoid call to __dev_set_promiscuity()
while rtnl_mutex isn't held") when conecting one of this switch's port
to a DSA switch as the conduit interface, the network interface is set to
promiscuous mode by default and cannot be set to not promiscuous mode again
from userspace. The reason for this is that the cpsw ports net devices
do not have the flag IFF_UNICAST_FLT set in their private flags.

The cpsw switch should be able to set not promiscuous mode as otherwise
a '1' is written to bit ALE_PORT_MACONLY_CAF which makes ethernet frames
get an additional VLAN tag when entering the port connected to the DSA
switch. Setting the IFF_UNICAST_FLT flag to all ports allows us to have
the conduit interface on the DSA subsystem set as not promiscuous.

It doesn't look like am65-cpsw-nuss supports unicast filtering, 
tho, does it? So we're lying about support to work around some 
CPSW weirdness (additional VLAN tag thing)?

I considered that as well, it is also not clear to me if this actually
works. At minimum the description needs additions.

The interesting thing here is, this is a switch port. If there is an
entry in the FDB, that is as good as a unicast filter.

Now, i've no idea if this actually works. This is more Vladimirs
area. What especially needs testing is a port not a member of a
bridge, when you don't really expect there to be any FDB entries.

	Andrew