net: dsa: b53: do not program vlans when vlan filtering is off

Documentation/networking/switchdev.rst says:

- with VLAN filtering turned off: the bridge is strictly VLAN unaware and its
  data path will process all Ethernet frames as if they are VLAN-untagged.
  The bridge VLAN database can still be modified, but the modifications should
  have no effect while VLAN filtering is turned off.

This breaks if we immediately apply the VLAN configuration, so skip
writing it when vlan_filtering is off.

Fixes: 0ee2af4 ("net: dsa: set configure_vlan_while_not_filtering to true by default")
Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
Tested-by: Florian Fainelli <florian.fainelli@broadcom.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Link: https://patch.msgid.link/20250429201710.330937-9-jonas.gorski@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: KanjiMonster

drivers/net/dsa/b53/b53_common.c

@@ -1547,6 +1547,9 @@ int b53_vlan_add(struct dsa_switch *ds, int port,
 	if (vlan->vid == 0)
 		return 0;
 
+	if (!ds->vlan_filtering)
+		return 0;
+
 	b53_read16(dev, B53_VLAN_PAGE, B53_VLAN_PORT_DEF_TAG(port), &old_pvid);
 	if (pvid)
 		new_pvid = vlan->vid;
@@ -1592,6 +1595,9 @@ int b53_vlan_del(struct dsa_switch *ds, int port,
 	if (vlan->vid == 0)
 		return 0;
 
+	if (!ds->vlan_filtering)
+		return 0;
+
 	b53_read16(dev, B53_VLAN_PAGE, B53_VLAN_PORT_DEF_TAG(port), &pvid);
 
 	vl = &dev->vlans[vlan->vid];
@@ -1952,18 +1958,20 @@ int b53_br_join(struct dsa_switch *ds, int port, struct dsa_bridge bridge,
 	pvid = b53_default_pvid(dev);
 	vl = &dev->vlans[pvid];
 
-	/* Make this port leave the all VLANs join since we will have proper
-	 * VLAN entries from now on
-	 */
-	if (is58xx(dev)) {
-		b53_read16(dev, B53_VLAN_PAGE, B53_JOIN_ALL_VLAN_EN, &reg);
-		reg &= ~BIT(port);
-		if ((reg & BIT(cpu_port)) == BIT(cpu_port))
-			reg &= ~BIT(cpu_port);
-		b53_write16(dev, B53_VLAN_PAGE, B53_JOIN_ALL_VLAN_EN, reg);
-	}
-
 	if (ds->vlan_filtering) {
+		/* Make this port leave the all VLANs join since we will have
+		 * proper VLAN entries from now on
+		 */
+		if (is58xx(dev)) {
+			b53_read16(dev, B53_VLAN_PAGE, B53_JOIN_ALL_VLAN_EN,
+				   &reg);
+			reg &= ~BIT(port);
+			if ((reg & BIT(cpu_port)) == BIT(cpu_port))
+				reg &= ~BIT(cpu_port);
+			b53_write16(dev, B53_VLAN_PAGE, B53_JOIN_ALL_VLAN_EN,
+				    reg);
+		}
+
 		b53_get_vlan_entry(dev, pvid, vl);
 		vl->members &= ~BIT(port);
 		if (vl->members == BIT(cpu_port))
@@ -2030,16 +2038,16 @@ void b53_br_leave(struct dsa_switch *ds, int port, struct dsa_bridge bridge)
 	pvid = b53_default_pvid(dev);
 	vl = &dev->vlans[pvid];
 
-	/* Make this port join all VLANs without VLAN entries */
-	if (is58xx(dev)) {
-		b53_read16(dev, B53_VLAN_PAGE, B53_JOIN_ALL_VLAN_EN, &reg);
-		reg |= BIT(port);
-		if (!(reg & BIT(cpu_port)))
-			reg |= BIT(cpu_port);
-		b53_write16(dev, B53_VLAN_PAGE, B53_JOIN_ALL_VLAN_EN, reg);
-	}
-
 	if (ds->vlan_filtering) {
+		/* Make this port join all VLANs without VLAN entries */
+		if (is58xx(dev)) {
+			b53_read16(dev, B53_VLAN_PAGE, B53_JOIN_ALL_VLAN_EN, &reg);
+			reg |= BIT(port);
+			if (!(reg & BIT(cpu_port)))
+				reg |= BIT(cpu_port);
+			b53_write16(dev, B53_VLAN_PAGE, B53_JOIN_ALL_VLAN_EN, reg);
+		}
+
 		b53_get_vlan_entry(dev, pvid, vl);
 		vl->members |= BIT(port) | BIT(cpu_port);
 		vl->untag |= BIT(port) | BIT(cpu_port);