On Thu, Aug 6, 2015 at 2:52 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > On Thu, 6 Aug 2015, Laszlo Papp wrote: > >> Hi Alan, >> >> On Wed, Aug 5, 2015 at 7:15 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: >> > On Wed, 5 Aug 2015, Greg KH wrote: >> > >> >> hm, wait, is this really the n_gsm line discipline? Or is it something >> >> else? >> >> >> >> g_serial is the device side of a serial connection, there is no "cable >> >> removed" notification that it even knows about, that has to come from >> >> the gadget driver somehow, which you should listen for and then kick >> >> your userspace program. >> > >> > There is the gserial_disconnect() callback, which gets invoked when the >> > Vbus power (provided by the host) is removed. It's a pretty good >> > indicator that the USB cable has been unplugged. >> > >> > I don't understand all the stuff that gserial_disconnect() does, but it >> > ought to be more or less equivalent to a "hangup" -- as the kerneldoc >> > says. If it doesn't do what users expect, there's probably a bug >> > somewhere. >> > >> > Of course, it's possible that the callback does not get invoked in >> > Laszlo's case. Then the question would be: Why not? >> >> Hmm, that is a good question. I wonder if there had been any recent >> fixes for that lately... I suppose that I will need to skim through >> the git log. Thank you for the hints! > > You should also add a printk statement to the disconnect callback so > that you can verify whether it really is getting called. Thanks. Should that also be called if I just boot up the board with Linux on it while the cable is not attached. In other words, the problem that I am also experiencing is that it blocks even when no cable is attached to the board and there has been no cable ever attached for the last boot. > > Alan Stern > -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
