[patch 18/29] USB: ftdi_sio: Update RTS and DTR simultaneously

Greg KH
2005-07-30T00:50:38Z

[-- Attachment #1: usb-ftdi_sio-rts-dtr.patch --]
[-- Type: text/plain, Size: 6127 bytes --]

From: Ian Abbott <abbotti@mev.co.uk>

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 <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/usb/serial/ftdi_sio.c | 138 +++++++++++++-----------------------------
1 files changed, 43 insertions(+), 95 deletions(-)

--- gregkh-2.6.orig/drivers/usb/serial/ftdi_sio.c 2005-07-29 11:36:25.000000000 -0700
+++ gregkh-2.6/drivers/usb/serial/ftdi_sio.c 2005-07-29 11:36:26.000000000 -0700
@@ -596,62 +596,59 @@
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;
}

@@ -1222,12 +1219,7 @@
/* 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);
@@ -1277,14 +1269,8 @@
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 */
@@ -1815,25 +1801,14 @@
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 */
@@ -1945,35 +1920,8 @@

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);
}

--