Serial: Avoid unbalanced IRQ wake disable during resume

To avoid unbalanced IRQ wake disable, ensure that wakeups are disabled
only when wakeups have been successfully enabled.
Tested on OMAP3630SDP/ZOOM3.

Signed-off-by: Govindraj.R <govindraj.raja@ti.com>
Reported-by: Paul Walmsley <paul@pwsan.com>
Cc: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/serial/serial_core.c

@@ -1986,7 +1986,8 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *uport)
 
 	tty_dev = device_find_child(uport->dev, &match, serial_match_port);
 	if (device_may_wakeup(tty_dev)) {
-		enable_irq_wake(uport->irq);
+		if (!enable_irq_wake(uport->irq))
+			uport->irq_wake = 1;
 		put_device(tty_dev);
 		mutex_unlock(&port->mutex);
 		return 0;
@@ -2052,7 +2053,10 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *uport)
 
 	tty_dev = device_find_child(uport->dev, &match, serial_match_port);
 	if (!uport->suspended && device_may_wakeup(tty_dev)) {
-		disable_irq_wake(uport->irq);
+		if (uport->irq_wake) {
+			disable_irq_wake(uport->irq);
+			uport->irq_wake = 0;
+		}
 		mutex_unlock(&port->mutex);
 		return 0;
 	}

include/linux/serial_core.h

@@ -365,6 +365,7 @@ struct uart_port {
 	struct device		*dev;			/* parent device */
 	unsigned char		hub6;			/* this should be in the 8250 driver */
 	unsigned char		suspended;
+	unsigned char		irq_wake;
 	unsigned char		unused[2];
 	void			*private_data;		/* generic platform data pointer */
 };