1 files changed, 21 insertions, 9 deletions

diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index cf75beb1251b..4753c005cfb6 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -359,20 +359,29 @@ static int serial_chars_in_buffer(struct tty_struct *tty)
 {
         struct usb_serial_port *port = tty->driver_data;
         struct usb_serial *serial = port->serial;
-        int count = 0;
 
         dev_dbg(tty->dev, "%s\n", __func__);
 
-        mutex_lock(&serial->disc_mutex);
-        /* if the device was unplugged then any remaining characters
-           fell out of the connector ;) */
         if (serial->disconnected)
-                count = 0;
-        else
-                count = serial->type->chars_in_buffer(tty);
-        mutex_unlock(&serial->disc_mutex);
+                return 0;
+
+        return serial->type->chars_in_buffer(tty);
+}
+
+static void serial_wait_until_sent(struct tty_struct *tty, int timeout)
+{
+        struct usb_serial_port *port = tty->driver_data;
+        struct usb_serial *serial = port->serial;
+
+        dev_dbg(tty->dev, "%s\n", __func__);
+
+        if (!port->serial->type->wait_until_sent)
+                return;
 
-        return count;
+        mutex_lock(&serial->disc_mutex);
+        if (!serial->disconnected)
+                port->serial->type->wait_until_sent(tty, timeout);
+        mutex_unlock(&serial->disc_mutex);
 }
 
 static void serial_throttle(struct tty_struct *tty)
@@ -1191,6 +1200,7 @@ static const struct tty_operations serial_ops = {
         .unthrottle =           serial_unthrottle,
         .break_ctl =            serial_break,
         .chars_in_buffer =      serial_chars_in_buffer,
+        .wait_until_sent =      serial_wait_until_sent,
         .tiocmget =             serial_tiocmget,
         .tiocmset =             serial_tiocmset,
         .get_icount =           serial_get_icount,
@@ -1316,6 +1326,8 @@ static void usb_serial_operations_init(struct usb_serial_driver *device)
         set_to_generic_if_null(device, close);
         set_to_generic_if_null(device, write_room);
         set_to_generic_if_null(device, chars_in_buffer);
+        if (device->tx_empty)
+                set_to_generic_if_null(device, wait_until_sent);
         set_to_generic_if_null(device, read_bulk_callback);
         set_to_generic_if_null(device, write_bulk_callback);
         set_to_generic_if_null(device, process_read_urb);