On 07/15/2016 06:31 PM, Dmitry Torokhov wrote: > Hi Hans, > > On Fri, Jul 15, 2016 at 01:27:21PM +0200, Hans Verkuil wrote: >> For the upcoming 4.8 kernel I made a driver for the Pulse-Eight USB CEC adapter. >> This is a usb device that shows up as a ttyACM0 device. It requires that you run >> inputattach in order to communicate with it via serio. >> >> This all works well, but it would be nice to have a udev rule to automatically >> start inputattach. That too works OK, but the problem comes when the USB device >> is unplugged: the tty hangup is never handled by the serio framework so the >> inputattach utility never exits and you have to kill it manually. >> >> By adding this hangup callback the inputattach utility now exists as soon as I >> unplug the USB device. >> >> Is this the correct approach? >> >> BTW, the new driver is found here: >> >> https://git.linuxtv.org/media_tree.git/tree/drivers/staging/media/pulse8-cec >> >> Regards, >> >> Hans >> >> Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx> >> >> --- >> diff --git a/drivers/input/serio/serport.c b/drivers/input/serio/serport.c >> index 9c927d3..a615846 100644 >> --- a/drivers/input/serio/serport.c >> +++ b/drivers/input/serio/serport.c >> @@ -248,6 +248,14 @@ static long serport_ldisc_compat_ioctl(struct tty_struct *tty, >> } >> #endif >> >> +static int serport_ldisc_hangup(struct tty_struct * tty) >> +{ >> + struct serport *serport = (struct serport *) tty->disc_data; >> + >> + serport_serio_close(serport->serio); > > I see what you mean, but this is not quite correct. I think we should > make serport_serio_close() only reset the SERPORT_ACTIVE flag and have > serport_ldisc_hangup() actually do: > > spin_lock_irqsave(&serport->lock, flags); > set_bit(SERPORT_DEAD, &serport->flags); > spin_unlock_irqrestore(&serport->lock, flags); > > wake_up_interruptible(&serport->wait); I'm preparing a v2 of this patch, but I wonder if in this hangup code I also need to clear the SERPORT_ACTIVE flag. Or is it guaranteed that close() always precedes hangup()? In which case close() always clears that flag. Regards, Hans > > i.e. if user (via device-driver - input core - evdev - userspace chain) > stops using serio port we should not kill inputattach instance right > then and there, but wait for the serial port device disconnect or > something else killing inputattach. > > Vojtech, do you recall any of this code? > > Thanks. > -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
