quoted

+static int dsa_port_devlink_setup(struct dsa_port *dp)
 {
 	struct devlink_port *dlp = &dp->devlink_port;
+	struct dsa_switch_tree *dst = dp->ds->dst;
+	struct devlink_port_attrs attrs = {};
+	struct devlink *dl = dp->ds->devlink;
+	const unsigned char *id;
+	unsigned char len;
+	int err;
+
+	id = (const unsigned char *)&dst->index;
+	len = sizeof(dst->index);
+
+	attrs.phys.port_number = dp->index;
+	memcpy(attrs.switch_id.id, id, len);
+	attrs.switch_id.id_len = len;
+
+	if (dp->setup)
+		return 0;
 

I wonder what this is protecting against? I ran on a multi-switch tree
without these 2 lines and I didn't get anything like multiple
registration or things like that. What is the call path that would call
dsa_port_devlink_setup twice?

I made a duplicate copy of dsa_port_setup() and trimmed out what was
not needed to give the new dsa_port_setup() and
dsa_port_devlink_setup(). I did not trim enough...

quoted

+	switch (dp->type) {
+	case DSA_PORT_TYPE_UNUSED:
+		memset(dlp, 0, sizeof(*dlp));
+		attrs.flavour = DEVLINK_PORT_FLAVOUR_UNUSED;

quoted

+		devlink_port_attrs_set(dlp, &attrs);
+		err = devlink_port_register(dl, dlp, dp->index);

These 2 lines are common everywhere. Could you move them out of the
switch-case statement?

Yes, that makes sense. Too much blind copy/paste without actually
reviewing the code afterwards.

	  Andrew