USB: serial: ftdi_sio: clean up flow control management
Clean up the somewhat convoluted hardware-assisted flow control
handling.
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index 3d7f181..b5cef32 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");
- }
- } 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);
+ /* Set hardware-assisted flow control */
+ value = 0;
- 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");
- }
- }
+ 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 {
+ 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);
}
/*
