Prevent MM form using a specific modem serial port

[Dan Williams]

On Thu, 2018-03-15 at 17:26 +0000, Jose, Shijo wrote:
> > > How do prevent MM from accessing one or all of the serial ports?
> > > 
> > > I have tried adding udev rules for MM to ignore only the serial
> > > ports 
> > > but this does not work
> > > 
> > > KERNEL=="ttyACM*", ENV{ID_MM_DEVICE_IGNORE}="1"
> > > 
> > Try with ID_MM_PORT_IGNORE.
> > And remember to re-trigger udev events (or rebooting) after adding
> > the tag:
> > $ sudo udevadm control --reload
> > $ sudo udevadm trigger
> > Also, you may want to upgrade to 1.8-rc1 or at least the latest
> > 1.6.x version. There should not be any reason to stay at 1.6.4.
> 
> Thanks for your quick response! It works
> Another question, does MM need to use the serial ports for proper
> functioning?
> Does it use the serial ports to initially send some mandatory AT
> commands besides poring them? 
> In other words, is it okay to have MM ignore all the ports except
> MBIM capable port?

We've discussed using ttys for GPS on MBIM devices (since MBIM does not
handle GPS) but I don't believe we've implemented that yet.

We might also want to implement the Signal API via AT commands on MBIM
modems that don't support AT&T Device Services, but that hasn't
happened yet either.

So for modems that MM drives via QMI and MBIM, ignoring AT ports should
be OK for now.

Dan