diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index 342e12f..e2eacdf 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -1908,14 +1908,18 @@ static int serial8250_startup(struct uart_port *port)
 		 * kick the UART on a regular basis.
 		 */
 		if (!(iir1 & UART_IIR_NO_INT) && (iir & UART_IIR_NO_INT)) {
+			up->bugs |= UART_BUG_THRE;
 			pr_debug("ttyS%d - using backup timer\n", port->line);
-			up->timer.function = serial8250_backup_timeout;
-			up->timer.data = (unsigned long)up;
-			mod_timer(&up->timer, jiffies +
-				poll_timeout(up->port.timeout) + HZ / 5);
 		}
 	}
 
+	if (up->bugs & UART_BUG_THRE) {
+		up->timer.function = serial8250_backup_timeout;
+		up->timer.data = (unsigned long)up;
+		mod_timer(&up->timer, jiffies +
+			  poll_timeout(up->port.timeout) + HZ / 5);
+	}
+
 	/*
 	 * If the "interrupt" for this port doesn't correspond with any
 	 * hardware interrupt, we use a timer-based system.  The original
diff --git a/drivers/serial/8250.h b/drivers/serial/8250.h
index 78c0016..5202603 100644
--- a/drivers/serial/8250.h
+++ b/drivers/serial/8250.h
@@ -47,6 +47,7 @@ struct serial8250_config {
 #define UART_BUG_QUOT	(1 << 0)	/* UART has buggy quot LSB */
 #define UART_BUG_TXEN	(1 << 1)	/* UART has buggy TX IIR status */
 #define UART_BUG_NOMSR	(1 << 2)	/* UART has buggy MSR status bits (Au1x00) */
+#define UART_BUG_THRE	(1 << 3)	/* UART has buggy THRE reassertion */
 
 #define PROBE_RSA	(1 << 0)
 #define PROBE_ANY	(~0)