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USB: serial: handle Data Carrier Detect changes

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Alan's commit 335f8514f2 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>
This commit is contained in:
Libor Pechacek
2011-01-14 14:30:21 +01:00
committed by Greg Kroah-Hartman
parent ca9cfea09f
commit d14fc1a74e
8 changed files with 50 additions and 40 deletions
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20
drivers/usb/serial/generic.c
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@@ -479,6 +479,26 @@ int usb_serial_handle_break(struct usb_serial_port *port)
}
EXPORT_SYMBOL_GPL(usb_serial_handle_break);
/**
* usb_serial_handle_dcd_change - handle a change of carrier detect state
* @port: usb_serial_port structure for the open port
* @tty: tty_struct structure for the port
* @status: new carrier detect status, nonzero if active
*/
void usb_serial_handle_dcd_change(struct usb_serial_port *usb_port,
struct tty_struct *tty, unsigned int status)
{
struct tty_port *port = &usb_port->port;
dbg("%s - port %d, status %d", __func__, usb_port->number, status);
if (status)
wake_up_interruptible(&port->open_wait);
else if (tty && !C_CLOCAL(tty))
tty_hangup(tty);
}
EXPORT_SYMBOL_GPL(usb_serial_handle_dcd_change);
int usb_serial_generic_resume(struct usb_serial *serial)
{
struct usb_serial_port *port;