Re: [PATCH net-next 2/3] net: dsa: Allow default tag protocol to be overridden from DT

Vladimir Oltean
2021-03-28T21:54:11Z

On Sun, Mar 28, 2021 at 05:52:43PM +0200, Andrew Lunn wrote:
> > +static int dsa_switch_setup_tag_protocol(struct dsa_switch *ds)
> > +{
> > + const struct dsa_device_ops *tag_ops = ds->dst->tag_ops;
> > + struct dsa_switch_tree *dst = ds->dst;
> > + int port, err;
> > +
> > + if (tag_ops->proto == dst->default_proto)
> > + return 0;
> > +
> > + if (!ds->ops->change_tag_protocol) {
> > + dev_err(ds->dev, "Tag protocol cannot be modified\n");
> > + return -EINVAL;
> > + }
> > +
> > + for (port = 0; port < ds->num_ports; port++) {
> > + if (!(dsa_is_dsa_port(ds, port) || dsa_is_cpu_port(ds, port)))
> > + continue;
>
> dsa_is_dsa_port() is interesting. Do we care about the tagging
> protocol on DSA ports? We never see that traffic?

I believe this comes from me (see dsa_switch_tag_proto_match). I did not
take into consideration at that time the fact that Marvell switches can
translate between DSA and EDSA. So I assumed that every switch in the
tree needs a notification about the tagging protocol, not just the
top-most one.