Re: [PATCH v2 net-next 2/6] net: dsa: propagate flags down towards drivers

Vladimir Oltean
2023-03-30T15:45:23Z

On Thu, Mar 30, 2023 at 05:34:44PM +0200, Hans Schultz wrote:
> On Thu, Mar 30, 2023 at 18:07, Vladimir Oltean <olteanv@gmail.com> wrote:
> >
> > Then, make DSA decide whether to handle the "added_by_user && !is_static"
> > combination or not, based on the presence of the DSA_FDB_FLAG_DYNAMIC
> > flag, which will be set in ds->supported_fdb_flags only for the mv88e6xxx
> > driver.
>
> Okay, so this will require a new function in the DSA layer that sets
> which flags are supported and that the driver will call on
> initialization.
>
> Where (in the DSA layer) should such a function be placed and what
> should it be called?

Don't overthink it, no new function. It's okay to just set
ds->supported_fdb_flags = DSA_FDB_FLAG_DYNAMIC in
mv88e6xxx_register_switch(), near the place where it currently sets
ds->num_lag_ids. Either before dsa_register_switch(), or within the
ds->ops->setup(). Both are fine, since the user network interfaces
haven't been allocated just yet by dsa_slave_create() and so, the
switchdev code path is inaccessible.

Existing drivers will have ds->supported_fdb_flags = 0 by default, since
they allocate the struct dsa_switch with kzalloc(), and DSA will have to
do something sane with that.