USB: ftdi_sio: optimise chars_in_buffer

No need to check hardware buffers when we know that the software
buffers are non-empty.

Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index 9fe3a2e..b8bc9d0 100644 (file)
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -2098,6 +2098,8 @@ static int ftdi_chars_in_buffer(struct tty_struct *tty)
        int ret;
 
        chars = usb_serial_generic_chars_in_buffer(tty);
+       if (chars)
+               return chars;
 
        /* Check hardware buffer */
        switch (priv->chip_type) {