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Commit a37025b5 authored by Johan Hovold's avatar Johan Hovold Committed by Greg Kroah-Hartman
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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: default avatarStas Sergeev <stsp@list.ru>
Signed-off-by: default avatarJohan Hovold <jhovold@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent c4133648

drivers/usb/serial/ftdi_sio.c

+5 −14
Original line number Diff line number Diff line
@@ -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