diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c
index 45295ca095717314294e1be8172a6e852fe1a679..2bc62ea857c8b6842c27ed9d6ee12b564fb2d1e6 100644
--- a/net/dsa/dsa.c
+++ b/net/dsa/dsa.c
@@ -80,6 +80,7 @@ dsa_switch_setup(struct dsa_switch_tree *dst, int index,
 	int ret;
 	char *name;
 	int i;
+	bool valid_name_found = false;
 
 	/*
 	 * Probe for switch model.
@@ -131,8 +132,13 @@ dsa_switch_setup(struct dsa_switch_tree *dst, int index,
 		} else {
 			ds->phys_port_mask |= 1 << i;
 		}
+		valid_name_found = true;
 	}
 
+	if (!valid_name_found && i == DSA_MAX_PORTS) {
+		ret = -EINVAL;
+		goto out;
+	}
 
 	/*
 	 * If the CPU connects to this switch, set the switch tree
diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index f4345582a6b9e3f5067cb7df0b5bf8bdd77e3b14..6ebd8fbd92855763013b5feefbb8123e0ee7fe3e 100644
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -41,8 +41,8 @@ void dsa_slave_mii_bus_init(struct dsa_switch *ds)
 	ds->slave_mii_bus->name = "dsa slave smi";
 	ds->slave_mii_bus->read = dsa_slave_phy_read;
 	ds->slave_mii_bus->write = dsa_slave_phy_write;
-	snprintf(ds->slave_mii_bus->id, MII_BUS_ID_SIZE, "%s:%.2x",
-			ds->master_mii_bus->id, ds->pd->sw_addr);
+	snprintf(ds->slave_mii_bus->id, MII_BUS_ID_SIZE, "dsa-%d:%.2x",
+			ds->index, ds->pd->sw_addr);
 	ds->slave_mii_bus->parent = &ds->master_mii_bus->dev;
 }