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Subject[040/119] tty: cp210x: Fix carrier handling
2.6.31-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Alan Cox <alan@linux.intel.com>

commit d94c7bd4c1361cab58a21d530078c5673863dcc2 upstream.

Original discussion:
http://thread.gmane.org/gmane.linux.usb.general/23217/focus=23248
or
http://marc.info/?l=linux-usb&m=125553790714133&w=2

9a68e39d4a701fb3be03cae9b462408664ebd205 broke carrier handling so that a
cp210x setup which needed the carrier lines set up (non CLOCAL) which did
not make a call which set the termios bits left the lines down even if
CLOCAL was not asserted.

Fix this not by reverting but by adding the proper dtr_rts and
carrier_raised methods. This both sets the modem lines properly and also
implements the correct blocking semantics for the port as required by
POSIX.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Reported-by: Karl Hiramoto <karl@hiramoto.org>
Tested-by: Karl Hiramoto <karl@hiramoto.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/usb/serial/cp210x.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)

--- a/drivers/usb/serial/cp210x.c
+++ b/drivers/usb/serial/cp210x.c
@@ -51,6 +51,8 @@ static int cp210x_tiocmset_port(struct u
static void cp210x_break_ctl(struct tty_struct *, int);
static int cp210x_startup(struct usb_serial *);
static void cp210x_disconnect(struct usb_serial *);
+static void cp210x_dtr_rts(struct usb_serial_port *p, int on);
+static int cp210x_carrier_raised(struct usb_serial_port *p);

static int debug;

@@ -144,6 +146,8 @@ static struct usb_serial_driver cp210x_d
.tiocmset = cp210x_tiocmset,
.attach = cp210x_startup,
.disconnect = cp210x_disconnect,
+ .dtr_rts = cp210x_dtr_rts,
+ .carrier_raised = cp210x_carrier_raised
};

/* Config request types */
@@ -748,6 +752,14 @@ static int cp210x_tiocmset_port(struct u
return cp210x_set_config(port, CP210X_SET_MHS, &control, 2);
}

+static void cp210x_dtr_rts(struct usb_serial_port *p, int on)
+{
+ if (on)
+ cp210x_tiocmset_port(p, NULL, TIOCM_DTR|TIOCM_RTS, 0);
+ else
+ cp210x_tiocmset_port(p, NULL, 0, TIOCM_DTR|TIOCM_RTS);
+}
+
static int cp210x_tiocmget (struct tty_struct *tty, struct file *file)
{
struct usb_serial_port *port = tty->driver_data;
@@ -770,6 +782,15 @@ static int cp210x_tiocmget (struct tty_s
return result;
}

+static int cp210x_carrier_raised(struct usb_serial_port *p)
+{
+ unsigned int control;
+ cp210x_get_config(p, CP210X_GET_MDMSTS, &control, 1);
+ if (control & CONTROL_DCD)
+ return 1;
+ return 0;
+}
+
static void cp210x_break_ctl (struct tty_struct *tty, int break_state)
{
struct usb_serial_port *port = tty->driver_data;



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