On Sun, 2012-02-26 at 19:48 +0100, Maik Zumstrull wrote: > On Sun, Feb 26, 2012 at 18:57, Greg KH <greg@xxxxxxxxx> wrote: > > On Sun, Feb 26, 2012 at 06:35:43PM +0100, Maik Zumstrull wrote: > > >> > Is the device stuck doing something? > >> > >> Not as far as I know. > > > > Are two userspace programs trying to access the device at the same time? > > The device exports three virtual serial ports. ModemManager accesses > more than one. On the other hand, we were able to reproduce the freeze > accessing only one port from one process, see Bugzilla. > > I've attached a fresh strace of opening the device on 3.2.6. The > open() takes 10s, the close takes 5s. Nothing else was accessing any > ttyUSB*; I killed ModemManager and double checked with lsof. > > > Yes. Please try loading the module with: > > modprobe option debug=1 > > and seeing what happens in the kernel log when you open the device. > > Output attached. I think it's three "option_send_setup" for one > open()/close(). At least, that's what happens with the C snippet. Ah, yeah, that would make sense. Does this happen for *all* ports on the modem, or only a few ports? I'd expect option_send_setup() to work for any AT-capable ports, but possibly fail for others that aren't full serial ports, like DIAG/DM ports or other protocols. There's a blacklist in option specifically for sendsetup that we can use to ensure that ports that don't like sendsetup don't use it. But we need to figure out which ports those are, since it's very unlikely to be all of them. Dan -- 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
