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USB: ftdi_sio: fix chars_in_buffer overhead 

Use the new generic usb-serial wait_until_sent implementation to wait
for hardware buffers to drain.

This removes the need to check the hardware buffers in chars_in_buffer
and thus removes the overhead introduced by commit 6f602912 ("usb:
serial: ftdi_sio: Add missing chars_in_buffer function") without
breaking tty_wait_until_sent (used by, for example, tcdrain, tcsendbreak
and close).

Reported-by: Stas Sergeev <stsp@list.ru>
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Johan Hovold 2013-05-05 20:32:30 +02:00 committed by Greg Kroah-Hartman
parent c4133648bb
commit a37025b5c7
1 changed files with 5 additions and 14 deletions
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19
drivers/usb/serial/ftdi_sio.c
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@ -924,7 +924,7 @@ static int ftdi_tiocmset(struct tty_struct *tty,
static int ftdi_ioctl(struct tty_struct *tty,
unsigned int cmd, unsigned long arg);
static void ftdi_break_ctl(struct tty_struct *tty, int break_state);
static int ftdi_chars_in_buffer(struct tty_struct *tty);
static bool ftdi_tx_empty(struct usb_serial_port *port);
static int ftdi_get_modem_status(struct usb_serial_port *port,
unsigned char status[2]);
@ -961,7 +961,7 @@ static struct usb_serial_driver ftdi_sio_device = {
.ioctl = ftdi_ioctl,
.set_termios = ftdi_set_termios,
.break_ctl = ftdi_break_ctl,
.chars_in_buffer = ftdi_chars_in_buffer,
.tx_empty = ftdi_tx_empty,
};
static struct usb_serial_driver * const serial_drivers[] = {
@ -2056,27 +2056,18 @@ static void ftdi_break_ctl(struct tty_struct *tty, int break_state)
}
static int ftdi_chars_in_buffer(struct tty_struct *tty)
static bool ftdi_tx_empty(struct usb_serial_port *port)
{
struct usb_serial_port *port = tty->driver_data;
int chars;
unsigned char buf[2];
int ret;
chars = usb_serial_generic_chars_in_buffer(tty);
if (chars)
goto out;
/* Check if hardware buffer is empty. */
ret = ftdi_get_modem_status(port, buf);
if (ret == 2) {
if (!(buf[1] & FTDI_RS_TEMT))
chars = 1;
return false;
}
out:
dev_dbg(&port->dev, "%s - %d\n", __func__, chars);
return chars;
return true;
}
/* old_termios contains the original termios settings and tty->termios contains