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-rw-r--r--drivers/serial/8250.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index 6d0ce64163e..ea41f262645 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -1868,6 +1868,7 @@ static int serial8250_startup(struct uart_port *port)
}
if (is_real_interrupt(up->port.irq)) {
+ unsigned char iir1;
/*
* Test for UARTs that do not reassert THRE when the
* transmitter is idle and the interrupt has already
@@ -1881,7 +1882,7 @@ static int serial8250_startup(struct uart_port *port)
wait_for_xmitr(up, UART_LSR_THRE);
serial_out_sync(up, UART_IER, UART_IER_THRI);
udelay(1); /* allow THRE to set */
- serial_in(up, UART_IIR);
+ iir1 = serial_in(up, UART_IIR);
serial_out(up, UART_IER, 0);
serial_out_sync(up, UART_IER, UART_IER_THRI);
udelay(1); /* allow a working UART time to re-assert THRE */
@@ -1894,7 +1895,7 @@ static int serial8250_startup(struct uart_port *port)
* If the interrupt is not reasserted, setup a timer to
* kick the UART on a regular basis.
*/
- if (iir & UART_IIR_NO_INT) {
+ if (!(iir1 & UART_IIR_NO_INT) && (iir & UART_IIR_NO_INT)) {
pr_debug("ttyS%d - using backup timer\n", port->line);
up->timer.function = serial8250_backup_timeout;
up->timer.data = (unsigned long)up;