USB: serial: spcp8x5: drop broken carrier detect support

commit d37186b upstream.

The driver does not support modem status notifications and instead used
to fetch the modem status once at open() and subsequently operate on and
report stale state.

As part of fixing this, a call to fetch the status was added to
carrier_raised(), which does not work as that callback must not sleep
(e.g. unlike tiocmget()).

Drop the broken carrier detect support.

Fixes: e1ed212 ("USB: spcp8x5: add proper modem-status support")
Cc: stable@vger.kernel.org	# 3.10
Reported-by: syzbot+3b514b87202742f22c44@syzkaller.appspotmail.com
Link: https://lore.kernel.org/all/6a73cea2.01d0871a.3a0d52.000d.GAE@google.com
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: jhovold

drivers/usb/serial/spcp8x5.c

@@ -237,18 +237,6 @@ static void spcp8x5_set_work_mode(struct usb_serial_port *port, u16 value,
 		dev_err(&port->dev, "failed to set work mode: %d\n", ret);
 }
 
-static int spcp8x5_carrier_raised(struct usb_serial_port *port)
-{
-	u8 msr;
-	int ret;
-
-	ret = spcp8x5_get_msr(port, &msr);
-	if (ret || msr & MSR_STATUS_LINE_DCD)
-		return 1;
-
-	return 0;
-}
-
 static void spcp8x5_dtr_rts(struct usb_serial_port *port, int on)
 {
 	struct spcp8x5_private *priv = usb_get_serial_port_data(port);
@@ -460,7 +448,6 @@ static struct usb_serial_driver spcp8x5_device = {
 	.num_bulk_out		= 1,
 	.open			= spcp8x5_open,
 	.dtr_rts		= spcp8x5_dtr_rts,
-	.carrier_raised		= spcp8x5_carrier_raised,
 	.set_termios		= spcp8x5_set_termios,
 	.init_termios		= spcp8x5_init_termios,
 	.tiocmget		= spcp8x5_tiocmget,