[RFC PATCH net-next 2/5] net: dsa: propagate flags down towards drivers

[Vladimir Oltean]

On Wed, Jan 18, 2023 at 11:35:08PM +0100, netdev at kapio-technology.com wrote:
> I am not sure I understand you entirely.
> From my standpoint I see it as so: that until now any fdb entry coming to
> port_fdb_add() (or port_fdb_del()) are seen as static entries. And this
> changes nothing with respect to those static entries as how drivers handle
> them.

This is true; it is implicit that the port_fdb_add() and port_fdb_del()
DSA methods request switches to operate on static FDB entries (in hardware).

> When the new dynamic flag is true, all drivers will ignore it in patch #3,
> so basically nothing will change by that.

This is not true, because it assumes that DSA never called port_fdb_add()
up until now for bridge FDB entries with the BR_FDB_STATIC flag unset,
which is incorrect (it did).

So what will change is that drivers which used to react to those bridge
FDB entries will stop doing so.

> Then in patch #5 the dynamic flag is handled by the mv88e6xxx driver.
> 
> I don't know the assisted_learning_on_cpu_port feature you mention, but
> there has still not been anything but static entries going towards
> port_fdb_add() yet...

For starters, you can read the commit message of the patch that
introduced it, which is d5f19486cee7 ("net: dsa: listen for
SWITCHDEV_{FDB,DEL}_ADD_TO_DEVICE on foreign bridge neighbors").