thunderbolt: Disable PCIe extended encapsulation upon teardown properly

In case of PCIe tunnel teardown (including if caused by router unplug),
PCIe extended encapsulation bit should be cleared in downstream and
upstream routers accordingly.
Signed-off-by: Gil Fine <gil.fine@linux.intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

drivers/thunderbolt/tunnel.c

@@ -173,16 +173,28 @@ static int tb_pci_set_ext_encapsulation(struct tb_tunnel *tunnel, bool enable)
 	int ret;
 
 	/* Only supported of both routers are at least USB4 v2 */
-	if (tb_port_get_link_generation(port) < 4)
+	if ((usb4_switch_version(tunnel->src_port->sw) < 2) ||
+	   (usb4_switch_version(tunnel->dst_port->sw) < 2))
+		return 0;
+
+	if (enable && tb_port_get_link_generation(port) < 4)
 		return 0;
 
 	ret = usb4_pci_port_set_ext_encapsulation(tunnel->src_port, enable);
 	if (ret)
 		return ret;
 
+	/*
+	 * Downstream router could be unplugged so disable of encapsulation
+	 * in upstream router is still possible.
+	 */
 	ret = usb4_pci_port_set_ext_encapsulation(tunnel->dst_port, enable);
-	if (ret)
-		return ret;
+	if (ret) {
+		if (enable)
+			return ret;
+		if (ret != -ENODEV)
+			return ret;
+	}
 
 	tb_tunnel_dbg(tunnel, "extended encapsulation %s\n",
 		      str_enabled_disabled(enable));