On Fri, May 18, 2018 at 03:25:50PM +0200, Johan Hovold wrote:
> Clean up the somewhat convoluted hardware-assisted flow control
> handling.
>
> Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
> ---
> drivers/usb/serial/ftdi_sio.c | 81 ++++++++++-------------------------
> 1 file changed, 23 insertions(+), 58 deletions(-)
>
> diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
> index 3d7f181e7e2a..b5cef322826f 100644
> --- a/drivers/usb/serial/ftdi_sio.c
> +++ b/drivers/usb/serial/ftdi_sio.c
> @@ -2191,12 +2191,8 @@ static void ftdi_set_termios(struct tty_struct *tty,
> struct ftdi_private *priv = usb_get_serial_port_data(port);
> struct ktermios *termios = &tty->termios;
> unsigned int cflag = termios->c_cflag;
> - u16 value;
> -
> - /* Added for xon/xoff support */
> - unsigned int iflag = termios->c_iflag;
> - unsigned char vstop;
> - unsigned char vstart;
> + u16 value, index;
> + int ret;
>
> /* Force baud rate if this device requires it, unless it is set to
> B0. */
> @@ -2325,61 +2321,30 @@ static void ftdi_set_termios(struct tty_struct *tty,
> set_mctrl(port, TIOCM_DTR | TIOCM_RTS);
> }
>
> - /* Set flow control */
> - /* Note device also supports DTR/CD (ugh) and Xon/Xoff in hardware */
> no_c_cflag_changes:
> - if (cflag & CRTSCTS) {
> - dev_dbg(ddev, "%s Setting to CRTSCTS flow control\n", __func__);
> - if (usb_control_msg(dev,
> - usb_sndctrlpipe(dev, 0),
> - FTDI_SIO_SET_FLOW_CTRL_REQUEST,
> - FTDI_SIO_SET_FLOW_CTRL_REQUEST_TYPE,
> - 0 , (FTDI_SIO_RTS_CTS_HS | priv->interface),
> - NULL, 0, WDR_TIMEOUT) < 0) {
> - dev_err(ddev, "urb failed to set to rts/cts flow control\n");
> - }
> + /* Set hardware-assisted flow control */
> + value = 0;
> +
> + if (C_CRTSCTS(tty)) {
> + dev_dbg(&port->dev, "enabling rts/cts flow control\n");
> + index = FTDI_SIO_RTS_CTS_HS;
> + } else if (I_IXON(tty)) {
> + dev_dbg(&port->dev, "enabling xon/xoff flow control\n");
> + index = FTDI_SIO_XON_XOFF_HS;
> + value = STOP_CHAR(tty) << 8 | START_CHAR(tty);
> } else {
> - /*
> - * Xon/Xoff code
> - */
> - if (iflag & IXON) {
> - dev_dbg(ddev, "%s request to enable xonxoff iflag=%04x\n",
> - __func__, iflag);
> - /* Try to enable the XON/XOFF on the ftdi_sio
> - * Set the vstart and vstop -- could have been done up
> - * above where a lot of other dereferencing is done but
> - * that would be very inefficient as vstart and vstop
> - * are not always needed.
> - */
> - vstart = termios->c_cc[VSTART];
> - vstop = termios->c_cc[VSTOP];
> - value = (vstop << 8) | (vstart);
> -
> - if (usb_control_msg(dev,
> - usb_sndctrlpipe(dev, 0),
> - FTDI_SIO_SET_FLOW_CTRL_REQUEST,
> - FTDI_SIO_SET_FLOW_CTRL_REQUEST_TYPE,
> - value , (FTDI_SIO_XON_XOFF_HS
> - | priv->interface),
> - NULL, 0, WDR_TIMEOUT) < 0) {
> - dev_err(&port->dev, "urb failed to set to "
> - "xon/xoff flow control\n");
> - }
> - } else {
> - /* else clause to only run if cflag ! CRTSCTS and iflag
> - * ! XON. CHECKME Assuming XON/XOFF handled by tty
> - * stack - not by device */
> - dev_dbg(ddev, "%s Turning off hardware flow control\n", __func__);
> - if (usb_control_msg(dev,
> - usb_sndctrlpipe(dev, 0),
> - FTDI_SIO_SET_FLOW_CTRL_REQUEST,
> - FTDI_SIO_SET_FLOW_CTRL_REQUEST_TYPE,
> - 0, priv->interface,
> - NULL, 0, WDR_TIMEOUT) < 0) {
> - dev_err(ddev, "urb failed to clear flow control\n");
> - }
> - }
> + dev_dbg(&port->dev, "disabling flow control\n");
> + index = FTDI_SIO_DISABLE_FLOW_CTRL;
> }
> +
> + index |= priv->interface;
> +
> + ret = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
> + FTDI_SIO_SET_FLOW_CTRL_REQUEST,
> + FTDI_SIO_SET_FLOW_CTRL_REQUEST_TYPE,
> + value, index, NULL, 0, WDR_TIMEOUT);
> + if (ret < 0)
> + dev_err(&port->dev, "failed to set flow control: %d\n", ret);
> }
>
> /*
Wow, much simpler, nice work.
Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
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