USB: ti_usb_3410_5052: query hardware-buffer status in chars_in_buffer
authorJohan Hovold <jhovold@gmail.com>
Thu, 18 Apr 2013 15:33:21 +0000 (17:33 +0200)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Fri, 19 Apr 2013 17:24:13 +0000 (10:24 -0700)
Query hardware-buffer status in chars_in_buffer should the write fifo be
empty.

This is needed to make the tty layer wait for hardware buffers to drain
on close.

Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/usb/serial/ti_usb_3410_5052.c

index 3ed8ecafe59708bf1ede94d7858d66878f91bc92..062b6d872ea3b2e7178a80dd4b5e6ce4617e3634 100644 (file)
@@ -687,6 +687,8 @@ static int ti_chars_in_buffer(struct tty_struct *tty)
        struct ti_port *tport = usb_get_serial_port_data(port);
        int chars = 0;
        unsigned long flags;
+       int ret;
+       u8 lsr;
 
        if (tport == NULL)
                return 0;
@@ -695,6 +697,12 @@ static int ti_chars_in_buffer(struct tty_struct *tty)
        chars = kfifo_len(&tport->write_fifo);
        spin_unlock_irqrestore(&tport->tp_lock, flags);
 
+       if (!chars) {
+               ret = ti_get_lsr(tport, &lsr);
+               if (!ret && !(lsr & TI_LSR_TX_EMPTY))
+                       chars = 1;
+       }
+
        dev_dbg(&port->dev, "%s - returns %d\n", __func__, chars);
        return chars;
 }