Re: Sierra USB 306 - GetSignalQuality() fails when connected: "Could not parse the +CIND response"

On Mon, Nov 26, 2012 at 10:26 AM, Dan Williams <dcbw redhat com> wrote:
> On Fri, 2012-11-23 at 17:33 -0800, Kelsey Sigurdur wrote:
>> Hi folks,
>> Newb here. As the subject says,  GetSignalQuality() is failing with
>> the error "Could not parse the +CIND response" when connected to the
>> network. When disconnected but enabled GetSignalQuality() properly
>> returns a value.
>> I'm just looking to find out if this is a issue with the hardware or
>> perhaps a bug in ModemManager.
>> I've scoured the archives as far back as January 2011 and the closest
>> problem to mine that I've found so far is the following thread, which
>> wasn't followed up on:
>> "Re: how to get signal strength of EVDO modem"
> So here's what's going on.
> 1) you don't appear to have the sierra_net driver on your system, or if
> you do, it's not bound to the USB 306.  The USB 306 should expose a
> network port as well as a few serial TTYs, and ModemManager should pick
> that network port up.  The logs you posted indicate that the kernel
> isn't binding sierra_net to the USB 306, so this appears to be a kernel
> or modeswitch issue.
> 2) Because there's no network port, you only get one full-featured AT
> command port, which is used for PPP while connected.  The other
> AT-capable ports have limited AT command parsers which do not allow the
> AT+CIND command, which is why you get that error.  However, there's a
> bug in ModemManager where it should just report the signal quality
> obtained by +CSQ instead of returning an error.
> So, I'd suggest finding out why sierra_net isn't getting used, but I'll
> also fix the MM bug too.
> Dan

Thanks Dan.

I do have the sierra_net driver on my system but you are correct that
it's not getting bound to the device.

For now I'm guessing it's a kernel issue. Google, and my rudimentary
understanding of C, suggests that the USB 306 is blacklisted in
sierra.c but would work with a firmware version >= M3.0.
Unfortunately,  the Sierra Wireless site offers only M2_0_11_10AP as
the latest firmware for this device.

See if you're interested in where I
came across the blacklist info.

I'm off to investigate modeswitching. Thanks for the tips, I appreciate it.

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