Hi,
The attached patch for the ftdi_sio driver lets it update the RTS and
DTR signals using a single control URB instead of two. This avoids
problems with equipment caused by sometimes long time differences
between the RTS and DTR signals changing, as reported by Reinhard Bergmann.
Signed off by me in the attachment. Please apply. TIA.
It doesn't look like we'll be getting our colonies back anytime soon, so
Happy 4th of July!
Ian Abbott.
ftdi_sio: Update RTS and DTR simultaneously, using a single control URB
instead of separate control URBs for RTS and DTR. Reinhard Bergmann
observed time differences of up to 680 ms with his application on a
2.4.22 kernel when RTS and DTR were updated using separate control
URBs, which is unacceptable.
Signed-off-by: Ian Abbott <[EMAIL PROTECTED]>
diff -ur a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
--- a/drivers/usb/serial/ftdi_sio.c 2005-07-04 12:37:31.000000000 +0100
+++ b/drivers/usb/serial/ftdi_sio.c 2005-07-04 13:54:17.000000000 +0100
@@ -593,62 +593,59 @@
return(ftdi_232bm_baud_base_to_divisor(baud, 48000000));
}
-static int set_rts(struct usb_serial_port *port, int high_or_low)
+#define set_mctrl(port, set) update_mctrl((port), (set), 0)
+#define clear_mctrl(port, clear) update_mctrl((port), 0, (clear))
+
+static int update_mctrl(struct usb_serial_port *port, unsigned int set, unsigned int clear)
{
struct ftdi_private *priv = usb_get_serial_port_data(port);
char *buf;
- unsigned ftdi_high_or_low;
+ unsigned urb_value;
int rv;
-
- buf = kmalloc(1, GFP_NOIO);
- if (!buf)
- return -ENOMEM;
-
- if (high_or_low) {
- ftdi_high_or_low = FTDI_SIO_SET_RTS_HIGH;
- priv->last_dtr_rts |= TIOCM_RTS;
- } else {
- ftdi_high_or_low = FTDI_SIO_SET_RTS_LOW;
- priv->last_dtr_rts &= ~TIOCM_RTS;
- }
- rv = usb_control_msg(port->serial->dev,
- usb_sndctrlpipe(port->serial->dev, 0),
- FTDI_SIO_SET_MODEM_CTRL_REQUEST,
- FTDI_SIO_SET_MODEM_CTRL_REQUEST_TYPE,
- ftdi_high_or_low, priv->interface,
- buf, 0, WDR_TIMEOUT);
-
- kfree(buf);
- return rv;
-}
+ if (((set | clear) & (TIOCM_DTR | TIOCM_RTS)) == 0) {
+ dbg("%s - DTR|RTS not being set|cleared", __FUNCTION__);
+ return 0; /* no change */
+ }
-static int set_dtr(struct usb_serial_port *port, int high_or_low)
-{
- struct ftdi_private *priv = usb_get_serial_port_data(port);
- char *buf;
- unsigned ftdi_high_or_low;
- int rv;
-
buf = kmalloc(1, GFP_NOIO);
- if (!buf)
+ if (!buf) {
return -ENOMEM;
-
- if (high_or_low) {
- ftdi_high_or_low = FTDI_SIO_SET_DTR_HIGH;
- priv->last_dtr_rts |= TIOCM_DTR;
- } else {
- ftdi_high_or_low = FTDI_SIO_SET_DTR_LOW;
- priv->last_dtr_rts &= ~TIOCM_DTR;
}
+
+ clear &= ~set; /* 'set' takes precedence over 'clear' */
+ urb_value = 0;
+ if (clear & TIOCM_DTR)
+ urb_value |= FTDI_SIO_SET_DTR_LOW;
+ if (clear & TIOCM_RTS)
+ urb_value |= FTDI_SIO_SET_RTS_LOW;
+ if (set & TIOCM_DTR)
+ urb_value |= FTDI_SIO_SET_DTR_HIGH;
+ if (set & TIOCM_RTS)
+ urb_value |= FTDI_SIO_SET_RTS_HIGH;
rv = usb_control_msg(port->serial->dev,
usb_sndctrlpipe(port->serial->dev, 0),
FTDI_SIO_SET_MODEM_CTRL_REQUEST,
FTDI_SIO_SET_MODEM_CTRL_REQUEST_TYPE,
- ftdi_high_or_low, priv->interface,
+ urb_value, priv->interface,
buf, 0, WDR_TIMEOUT);
kfree(buf);
+ if (rv < 0) {
+ err("%s Error from MODEM_CTRL urb: DTR %s, RTS %s",
+ __FUNCTION__,
+ (set & TIOCM_DTR) ? "HIGH" :
+ (clear & TIOCM_DTR) ? "LOW" : "unchanged",
+ (set & TIOCM_RTS) ? "HIGH" :
+ (clear & TIOCM_RTS) ? "LOW" : "unchanged");
+ } else {
+ dbg("%s - DTR %s, RTS %s", __FUNCTION__,
+ (set & TIOCM_DTR) ? "HIGH" :
+ (clear & TIOCM_DTR) ? "LOW" : "unchanged",
+ (set & TIOCM_RTS) ? "HIGH" :
+ (clear & TIOCM_RTS) ? "LOW" : "unchanged");
+ priv->last_dtr_rts = (priv->last_dtr_rts & ~clear) | set;
+ }
return rv;
}
@@ -1219,12 +1216,7 @@
/* FIXME: Flow control might be enabled, so it should be checked -
we have no control of defaults! */
/* Turn on RTS and DTR since we are not flow controlling by default */
- if (set_dtr(port, HIGH) < 0) {
- err("%s Error from DTR HIGH urb", __FUNCTION__);
- }
- if (set_rts(port, HIGH) < 0){
- err("%s Error from RTS HIGH urb", __FUNCTION__);
- }
+ set_mctrl(port, TIOCM_DTR | TIOCM_RTS);
/* Not throttled */
spin_lock_irqsave(&priv->rx_lock, flags);
@@ -1274,14 +1266,8 @@
err("error from flowcontrol urb");
}
- /* drop DTR */
- if (set_dtr(port, LOW) < 0){
- err("Error from DTR LOW urb");
- }
- /* drop RTS */
- if (set_rts(port, LOW) < 0) {
- err("Error from RTS LOW urb");
- }
+ /* drop RTS and DTR */
+ clear_mctrl(port, TIOCM_DTR | TIOCM_RTS);
} /* Note change no line if hupcl is off */
/* cancel any scheduled reading */
@@ -1812,25 +1798,14 @@
err("%s error from disable flowcontrol urb", __FUNCTION__);
}
/* Drop RTS and DTR */
- if (set_dtr(port, LOW) < 0){
- err("%s Error from DTR LOW urb", __FUNCTION__);
- }
- if (set_rts(port, LOW) < 0){
- err("%s Error from RTS LOW urb", __FUNCTION__);
- }
-
+ clear_mctrl(port, TIOCM_DTR | TIOCM_RTS);
} else {
/* set the baudrate determined before */
if (change_speed(port)) {
err("%s urb failed to set baurdrate", __FUNCTION__);
}
/* Ensure RTS and DTR are raised */
- else if (set_dtr(port, HIGH) < 0){
- err("%s Error from DTR HIGH urb", __FUNCTION__);
- }
- else if (set_rts(port, HIGH) < 0){
- err("%s Error from RTS HIGH urb", __FUNCTION__);
- }
+ set_mctrl(port, TIOCM_DTR | TIOCM_RTS);
}
/* Set flow control */
@@ -1942,35 +1917,8 @@
static int ftdi_tiocmset(struct usb_serial_port *port, struct file * file, unsigned int set, unsigned int clear)
{
- int ret;
-
dbg("%s TIOCMSET", __FUNCTION__);
- if (set & TIOCM_DTR){
- if ((ret = set_dtr(port, HIGH)) < 0) {
- err("Urb to set DTR failed");
- return(ret);
- }
- }
- if (set & TIOCM_RTS) {
- if ((ret = set_rts(port, HIGH)) < 0){
- err("Urb to set RTS failed");
- return(ret);
- }
- }
-
- if (clear & TIOCM_DTR){
- if ((ret = set_dtr(port, LOW)) < 0){
- err("Urb to unset DTR failed");
- return(ret);
- }
- }
- if (clear & TIOCM_RTS) {
- if ((ret = set_rts(port, LOW)) < 0){
- err("Urb to unset RTS failed");
- return(ret);
- }
- }
- return(0);
+ return update_mctrl(port, set, clear);
}
