serial: omap: make sure to put() on poll_get_char

if we would reach serial_omap_get_char() while
Data Ready bit isn't set, we would return from
it without kicking our pm timer. This would mean
we would, eventually, have an unbalanced
pm_runtime_get on our device which would prevent
it from ever sleeping again.

Tested-by: Shubhrajyoti D <shubhrajyoti@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 7 insertions, 2 deletions

diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index 7531147fbd38..6a58f4f64f81 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -1005,12 +1005,17 @@ static int serial_omap_poll_get_char(struct uart_port *port)
 
         pm_runtime_get_sync(up->dev);
         status = serial_in(up, UART_LSR);
-        if (!(status & UART_LSR_DR))
-                return NO_POLL_CHAR;
+        if (!(status & UART_LSR_DR)) {
+                status = NO_POLL_CHAR;
+                goto out;
+        }
 
         status = serial_in(up, UART_RX);
+
+out:
         pm_runtime_mark_last_busy(up->dev);
         pm_runtime_put_autosuspend(up->dev);
+
         return status;
 }