--- /dev/null
+From e4d127ddc83c5fbd93b9c8e2e4fe63b820ac28b6 Mon Sep 17 00:00:00 2001
+From: David Bauer <mail@david-bauer.net>
+Date: Sat, 22 May 2021 10:37:06 +0200
+Subject: [PATCH] common.c: fix kernel 5.10 builds with CONFIG_PM enabled
+
+Building the xr_usb_serial module fails for Kenel 5.10 with CONFIG_PM
+enabled:
+
+xr_usb_serial_common.c:1574:15: error: 'ASYNCB_INITIALIZED' undeclared
+(first use in this function); did you mean 'RCU_INITIALIZER'?
+
+Use tty_port_initialized in order to determine the status of the TTY
+port. This is compatible with Kernel 5.10 and at least Kernel 5.4.
+
+Signed-off-by: David Bauer <mail@david-bauer.net>
+---
+ xr_usb_serial_common-1a/xr_usb_serial_common.c | 6 +++---
+ 1 file changed, 3 insertions(+), 3 deletions(-)
+
+--- a/xr_usb_serial_common-1a/xr_usb_serial_common.c
++++ b/xr_usb_serial_common-1a/xr_usb_serial_common.c
+@@ -1571,7 +1571,7 @@ static int xr_usb_serial_suspend(struct
+ if (cnt)
+ return 0;
+
+- if (test_bit(ASYNCB_INITIALIZED, &xr_usb_serial->port.flags))
++ if (tty_port_initialized(&xr_usb_serial->port))
+ stop_data_traffic(xr_usb_serial);
+
+ return 0;
+@@ -1592,7 +1592,7 @@ static int xr_usb_serial_resume(struct u
+ if (cnt)
+ return 0;
+
+- if (test_bit(ASYNCB_INITIALIZED, &xr_usb_serial->port.flags)) {
++ if (tty_port_initialized(&xr_usb_serial->port)) {
+ rv = usb_submit_urb(xr_usb_serial->ctrlurb, GFP_NOIO);
+
+ spin_lock_irq(&xr_usb_serial->write_lock);
+@@ -1623,7 +1623,7 @@ static int xr_usb_serial_reset_resume(st
+ {
+ struct xr_usb_serial *xr_usb_serial = usb_get_intfdata(intf);
+ struct tty_struct *tty;
+- if (test_bit(ASYNCB_INITIALIZED, &xr_usb_serial->port.flags)){
++ if (tty_port_initialized(&xr_usb_serial->port)){
+ #if LINUX_VERSION_CODE > KERNEL_VERSION(3, 9, 0)
+ tty_port_tty_hangup(&xr_usb_serial->port, false);
+ #else