USB: serial: handle Data Carrier Detect changes

Alan's commit 335f8514f200e63d689113d29cb7253a5c282967 introduced
.carrier_raised function in several drivers.  That also means
tty_port_block_til_ready can now suspend the process trying to open the serial
port when Carrier Detect is low and put it into tty_port.open_wait queue.  We
need to wake up the process when Carrier Detect goes high and trigger TTY
hangup when CD goes low.

Some of the devices do not report modem status line changes, or at least we
don't understand the status message, so for those we remove .carrier_raised
again.

Signed-off-by: Libor Pechacek <lpechacek@suse.cz>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 1 insertions, 12 deletions

diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c
index c3bea46e87fb..735ea03157ab 100644
--- a/drivers/usb/serial/cp210x.c
+++ b/drivers/usb/serial/cp210x.c
@@ -49,7 +49,6 @@ 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_dtr_rts(struct usb_serial_port *p, int on);
-static int cp210x_carrier_raised(struct usb_serial_port *p);
 
 static int debug;
 
@@ -166,8 +165,7 @@ static struct usb_serial_driver cp210x_device = {
         .tiocmget               = cp210x_tiocmget,
         .tiocmset               = cp210x_tiocmset,
         .attach                 = cp210x_startup,
-        .dtr_rts                = cp210x_dtr_rts,
-        .carrier_raised         = cp210x_carrier_raised
+        .dtr_rts                = cp210x_dtr_rts
 };
 
 /* Config request types */
@@ -766,15 +764,6 @@ 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;