+static int ksz_hsr_join(struct dsa_switch *ds, int port, struct net_device *hsr)
+{
+	struct dsa_port *partner = NULL, *dp;
+	struct ksz_device *dev = ds->priv;
+	enum hsr_version ver;
+	int ret;
+
+	ret = hsr_get_version(hsr, &ver);
+	if (ret)
+		return ret;
+
+	switch (dev->chip_id) {
+	case KSZ9477_CHIP_ID:
+		if (ver == PRP_V1)
+			return -EOPNOTSUPP;

This should probably check for versions which are support, and not
assume PRP_V42 is not added some time in the future, which would be
accepted here.

	 Andrew