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Commit d94c7bd4 authored by Alan Cox's avatar Alan Cox Committed by Greg Kroah-Hartman
Browse files

tty: cp210x: Fix carrier handling 

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



9a68e39d 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: default avatarAlan Cox <alan@linux.intel.com>
Reported-by: default avatarKarl Hiramoto <karl@hiramoto.org>
Tested-by: default avatarKarl Hiramoto <karl@hiramoto.org>
Cc: stable <stable@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 4175f3e3

drivers/usb/serial/cp210x.c

+21 −0
Original line number Diff line number Diff line
@@ -50,6 +50,8 @@ static int cp210x_tiocmset_port(struct usb_serial_port *port, struct file *, 
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;
@@ -143,6 +145,8 @@ static struct usb_serial_driver cp210x_device = { 
	.tiocmset		= cp210x_tiocmset,

	.attach			= cp210x_startup,

	.disconnect		= cp210x_disconnect,

	.dtr_rts		= cp210x_dtr_rts,

	.carrier_raised		= cp210x_carrier_raised

};



/* Config request types */
@@ -746,6 +750,14 @@ static int cp210x_tiocmset_port(struct usb_serial_port *port, struct file *file, 
	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;
@@ -768,6 +780,15 @@ static int cp210x_tiocmget (struct tty_struct *tty, struct file *file) 
	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;