thunderbolt: Handle lane bonding of Gen 4 XDomain links properly

Gen 4 links come up as bonded already so we are not supposed to initiate
lane bonding on them. However, we should still update the port
structures accordingly. Split these into their own functions to make it
easier to follow.
Signed-off-by: Gil Fine <gil.fine@linux.intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

drivers/thunderbolt/tb.c

@@ -503,8 +503,6 @@ static void tb_port_unconfigure_xdomain(struct tb_port *port)
 		usb4_port_unconfigure_xdomain(port);
 	else
 		tb_lc_unconfigure_xdomain(port);
-
-	tb_port_enable(port->dual_link_port);
 }
 
 static void tb_scan_xdomain(struct tb_port *port)

drivers/thunderbolt/xdomain.c

@@ -1895,6 +1895,50 @@ struct device_type tb_xdomain_type = {
 };
 EXPORT_SYMBOL_GPL(tb_xdomain_type);
 
+static void tb_xdomain_link_init(struct tb_xdomain *xd, struct tb_port *down)
+{
+	if (!down->dual_link_port)
+		return;
+
+	/*
+	 * Gen 4 links come up already as bonded so only update the port
+	 * structures here.
+	 */
+	if (tb_port_get_link_generation(down) >= 4) {
+		down->bonded = true;
+		down->dual_link_port->bonded = true;
+	} else {
+		xd->bonding_possible = true;
+	}
+}
+
+static void tb_xdomain_link_exit(struct tb_xdomain *xd)
+{
+	struct tb_port *down = tb_xdomain_downstream_port(xd);
+
+	if (!down->dual_link_port)
+		return;
+
+	if (tb_port_get_link_generation(down) >= 4) {
+		down->bonded = false;
+		down->dual_link_port->bonded = false;
+	} else if (xd->link_width > TB_LINK_WIDTH_SINGLE) {
+		/*
+		 * Just return port structures back to way they were and
+		 * update credits. No need to update userspace because
+		 * the XDomain is removed soon anyway.
+		 */
+		tb_port_lane_bonding_disable(down);
+		tb_port_update_credits(down);
+	} else if (down->dual_link_port) {
+		/*
+		 * Re-enable the lane 1 adapter we disabled at the end
+		 * of tb_xdomain_get_properties().
+		 */
+		tb_port_enable(down->dual_link_port);
+	}
+}
+
 /**
  * tb_xdomain_alloc() - Allocate new XDomain object
  * @tb: Domain where the XDomain belongs
@@ -1945,7 +1989,8 @@ struct tb_xdomain *tb_xdomain_alloc(struct tb *tb, struct device *parent,
 			goto err_free_local_uuid;
 	} else {
 		xd->needs_uuid = true;
-		xd->bonding_possible = !!down->dual_link_port;
+
+		tb_xdomain_link_init(xd, down);
 	}
 
 	device_initialize(&xd->dev);
@@ -2014,6 +2059,8 @@ void tb_xdomain_remove(struct tb_xdomain *xd)
 
 	device_for_each_child_reverse(&xd->dev, xd, unregister_service);
 
+	tb_xdomain_link_exit(xd);
+
 	/*
 	 * Undo runtime PM here explicitly because it is possible that
 	 * the XDomain was never added to the bus and thus device_del()