diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
index e1c0bb24f5b2..29b79d6d2925 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.c
+++ b/drivers/net/dsa/mv88e6xxx/chip.c
@@ -1750,7 +1750,7 @@ static int mv88e6xxx_setup_upstream_port(struct mv88e6xxx_chip *chip, int port)
 	int upstream_port;
 	int err;
 
-	upstream_port = dsa_upstream_port(ds);
+	upstream_port = dsa_upstream_port(ds, port);
 	if (chip->info->ops->port_set_upstream_port) {
 		err = chip->info->ops->port_set_upstream_port(chip, port,
 							      upstream_port);
diff --git a/include/net/dsa.h b/include/net/dsa.h
index 8198efcc8ced..d29feccaefab 100644
--- a/include/net/dsa.h
+++ b/include/net/dsa.h
@@ -307,10 +307,13 @@ static inline unsigned int dsa_towards_port(struct dsa_switch *ds, int device,
 }
 
 /* Return the local port used to reach the dedicated CPU port */
-static inline u8 dsa_upstream_port(struct dsa_switch *ds)
+static inline unsigned int dsa_upstream_port(struct dsa_switch *ds, int port)
 {
-	struct dsa_switch_tree *dst = ds->dst;
-	struct dsa_port *cpu_dp = dst->cpu_dp;
+	const struct dsa_port *dp = dsa_to_port(ds, port);
+	const struct dsa_port *cpu_dp = dp->cpu_dp;
+
+	if (!cpu_dp)
+		return port;
 
 	return dsa_towards_port(ds, cpu_dp->ds->index, cpu_dp->index);
 }