[OpenWrt-Devel] NCM fails to reconnect

Tristan Collins tristan+openwrt at mailforce.net
Sun Feb 22 04:43:18 EST 2015

On Sun 22/02/15 10:27, Matti Laakso wrote:
> > From: Sami Olmari [mailto:sami at olmari.fi] 

> > It seems MCN protocol still has some quirks left... it seems that whenever MCN connection gets disconnected for whatever reason, it can't be > brought back up... even yanking the dongle out and back in does not do basically anything... it gets detected etc, but nothing else happends...
> >
> > following logread it shows literally nothing. Like NCM-script isn't there doing it's magic anymore... "ifup wan"... nothing.. etc.. Only full reboot makes it to work again, until next ocnnection breakup happends...
> >
> > What should we do?
> >
> > Sami Olmari
> Hi Sami,
> I think that this problem appears when the device is /dev/cdc-wdm* instead of /dev/ttyUSB*. In this case the 3g.usb-script from package comgt doesn't set the interface back to available upon plugging the dongle in (after it has been set unavailable with proto_set_available "$interface" 0). It seems that QMI and MBIM have the same problem. However, the "wwan" package has a suitable wwan.usbmisc-script (but it is missing NCM at the moment). So we should probably just add ncm to wwan.usbmisc and set wwan to be a dependency of comgt-ncm, uqmi and umbim.
> Matti

I'm also seeing this behaviour. Plugging in the dongle after a boot and issuing ifup wan does nothing.

In addition, I found that unless the NCM dongle is 'up and ready' before (re)booting (ie, has been powered up via a hub and left for a minute or so, with the status light progressing from, in my case, flashing green [GPRS] to flashing cyan [LTE]) no connection is made. No errors or anything written to log.

I experimented with option delay '30' but it made no difference.

This also has an impact on any scripts that need an external interface to be up. I need autossh to come up after wwan0 has made a connection, but with the current set up it is called well in advance of a connection being made; plays havoc with remote setup...

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