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USB: ti_usb_3410_5052: query hardware-buffer status in chars_in_buffer

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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>
This commit is contained in:
Johan Hovold 2013-04-18 17:33:21 +02:00 committed by Greg Kroah-Hartman
parent b5784f7d85
commit 2c992cd737
1 changed files with 8 additions and 0 deletions
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8
drivers/usb/serial/ti_usb_3410_5052.c
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@ -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;
}