diff --git a/include/net/dsa.h b/include/net/dsa.h
index b52e9b057be4..507082959aa4 100644
--- a/include/net/dsa.h
+++ b/include/net/dsa.h
@@ -149,6 +149,11 @@ struct dsa_switch_tree {
 	/* Tagging protocol operations */
 	const struct dsa_device_ops *tag_ops;
 
+	/* Default tagging protocol preferred by the switches in this
+	 * tree.
+	 */
+	enum dsa_tag_protocol default_proto;
+
 	/*
 	 * Configuration data for the platform device that owns
 	 * this dsa switch tree instance.
diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c
index d7c22e3a1fbf..b71e87909f0e 100644
--- a/net/dsa/dsa2.c
+++ b/net/dsa/dsa2.c
@@ -668,6 +668,30 @@ static const struct devlink_ops dsa_devlink_ops = {
 	.sb_occ_tc_port_bind_get	= dsa_devlink_sb_occ_tc_port_bind_get,
 };
 
+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;
+
+	for (port = 0; port < ds->num_ports; port++) {
+		if (!dsa_is_cpu_port(ds, port))
+			continue;
+
+		err = ds->ops->change_tag_protocol(ds, port, tag_ops->proto);
+		if (err) {
+			dev_err(ds->dev, "Unable to use tag protocol \"%s\": %pe\n",
+				tag_ops->name, ERR_PTR(err));
+			return err;
+		}
+	}
+
+	return 0;
+}
+
 static int dsa_switch_setup(struct dsa_switch *ds)
 {
 	struct dsa_devlink_priv *dl_priv;
@@ -718,6 +742,10 @@ static int dsa_switch_setup(struct dsa_switch *ds)
 	if (err < 0)
 		goto unregister_notifier;
 
+	err = dsa_switch_setup_tag_protocol(ds);
+	if (err)
+		goto teardown;
+
 	devlink_params_publish(ds->devlink);
 
 	if (!ds->slave_mii_bus && ds->ops->phy_read) {
@@ -1068,34 +1096,60 @@ static enum dsa_tag_protocol dsa_get_tag_protocol(struct dsa_port *dp,
 	return ds->ops->get_tag_protocol(ds, dp->index, tag_protocol);
 }
 
-static int dsa_port_parse_cpu(struct dsa_port *dp, struct net_device *master)
+static int dsa_port_parse_cpu(struct dsa_port *dp, struct net_device *master,
+			      const char *user_protocol)
 {
 	struct dsa_switch *ds = dp->ds;
 	struct dsa_switch_tree *dst = ds->dst;
 	const struct dsa_device_ops *tag_ops;
-	enum dsa_tag_protocol tag_protocol;
+	enum dsa_tag_protocol default_proto;
 
-	tag_protocol = dsa_get_tag_protocol(dp, master);
-	if (dst->tag_ops) {
-		if (dst->tag_ops->proto != tag_protocol) {
+	/* Find out which protocol the switch would prefer. */
+	default_proto = dsa_get_tag_protocol(dp, master);
+	if (dst->default_proto) {
+		if (dst->default_proto != default_proto) {
 			dev_err(ds->dev,
 				"A DSA switch tree can have only one tagging protocol\n");
 			return -EINVAL;
 		}
-		/* In the case of multiple CPU ports per switch, the tagging
-		 * protocol is still reference-counted only per switch tree, so
-		 * nothing to do here.
-		 */
 	} else {
-		tag_ops = dsa_tag_driver_get(tag_protocol);
-		if (IS_ERR(tag_ops)) {
-			if (PTR_ERR(tag_ops) == -ENOPROTOOPT)
-				return -EPROBE_DEFER;
-			dev_warn(ds->dev, "No tagger for this switch\n");
-			dp->master = NULL;
-			return PTR_ERR(tag_ops);
+		dst->default_proto = default_proto;
+	}
+
+	/* See if the user wants to override that preference. */
+	if (user_protocol) {
+		if (!ds->ops->change_tag_protocol) {
+			dev_err(ds->dev, "Tag protocol cannot be modified\n");
+			return -EINVAL;
 		}
 
+		tag_ops = dsa_find_tagger_by_name(user_protocol);
+	} else {
+		tag_ops = dsa_tag_driver_get(default_proto);
+	}
+
+	if (IS_ERR(tag_ops)) {
+		if (PTR_ERR(tag_ops) == -ENOPROTOOPT)
+			return -EPROBE_DEFER;
+
+		dev_warn(ds->dev, "No tagger for this switch\n");
+		return PTR_ERR(tag_ops);
+	}
+
+	if (dst->tag_ops) {
+		if (dst->tag_ops != tag_ops) {
+			dev_err(ds->dev,
+				"A DSA switch tree can have only one tagging protocol\n");
+
+			dsa_tag_driver_put(tag_ops);
+			return -EINVAL;
+		}
+
+		/* In the case of multiple CPU ports per switch, the tagging
+		 * protocol is still reference-counted only per switch tree.
+		 */
+		dsa_tag_driver_put(tag_ops);
+	} else {
 		dst->tag_ops = tag_ops;
 	}
 
@@ -1104,6 +1158,19 @@ static int dsa_port_parse_cpu(struct dsa_port *dp, struct net_device *master)
 	dsa_port_set_tag_protocol(dp, dst->tag_ops);
 	dp->dst = dst;
 
+	/* At this point, the tree may be configured to use a different
+	 * tagger than the one chosen by the switch driver during
+	 * .setup, in the case when a user selects a custom protocol
+	 * through the DT.
+	 *
+	 * This is resolved by syncing the driver with the tree in
+	 * dsa_switch_setup_tag_protocol once .setup has run and the
+	 * driver is ready to accept calls to .change_tag_protocol. If
+	 * the driver does not support the custom protocol at that
+	 * point, the tree is wholly rejected, thereby ensuring that the
+	 * tree and driver are always in agreement on the protocol to
+	 * use.
+	 */
 	return 0;
 }
 
@@ -1117,12 +1184,14 @@ static int dsa_port_parse_of(struct dsa_port *dp, struct device_node *dn)
 
 	if (ethernet) {
 		struct net_device *master;
+		const char *user_protocol;
 
 		master = of_find_net_device_by_node(ethernet);
 		if (!master)
 			return -EPROBE_DEFER;
 
-		return dsa_port_parse_cpu(dp, master);
+		user_protocol = of_get_property(dn, "dsa-tag-protocol", NULL);
+		return dsa_port_parse_cpu(dp, master, user_protocol);
 	}
 
 	if (link)
@@ -1234,7 +1303,7 @@ static int dsa_port_parse(struct dsa_port *dp, const char *name,
 
 		dev_put(master);
 
-		return dsa_port_parse_cpu(dp, master);
+		return dsa_port_parse_cpu(dp, master, NULL);
 	}
 
 	if (!strcmp(name, "dsa"))