Re: AW: Problems with Sierra MC 8790 with older firmware revision

[Dan Williams <dcbw redhat com>]

On Mon, 2013-02-25 at 16:42 +0100, Aleksander Morgado wrote:
> > On a side note, a user just reported an issue with a MC8790V (see the
> > trailing 'V' there), log attached. In this case, the issue is not about
> > using the APP1 port for PPP; the issue is that there is no non-APP port
> > shown, so we don't specify any port being 'primary', and we end up
> > choosing an incorrect one.
> >
> > So, with:
> >
> > ttyUSB3 --> APP1
> > ttyUSB4 --> APP2
> > ttyUSB5 --> APP3
> >
> > We end up getting:
> >
> > tty/ttyUSB4 primary
> > tty/ttyUSB3 secondary
> > tty/ttyUSB4 data
> >
> > And ttyUSB4 doesn't like being the primary port here. Possibly ttyUSB3
> > should be the one treated as primary?
>
> Well, after some tests, seems that the exposed APP ports in this device
> are like in any other Sierra device, with a limited AT command set, so
> we cannot use them as primary port... Now I wonder if lacking a proper
> primary AT port is a firmware/device bug or if they really did it on
> purpose (e.g. so that only CnS can be used).

That may well be the case.  There are some firmware commands to control
port configuration, but those are can be *very* harmful and we should
never be touching them in MM as we risk bricking the device, just like I
did to my first UMG1831 with AT^U2DIAG.  I think we're screwed here
unless we add CnS support, and we don't have docs for that since it's
proprietary.

THe only other thing I can think of is that maybe it's a driver bug, but
if the we have TTYs for all the USB interfaces shown in lsusb, then
that's not the problem.

Dan