FCC authentication with QMI over MBIM; try 1 -- Logs

Aleksander Morgado aleksander at aleksander.es
Fri Jul 1 11:12:33 UTC 2016

On Fri, Jul 1, 2016 at 1:05 PM, Bjørn Mork <bjorn at mork.no> wrote:
>>> See
>>> https://lists.freedesktop.org/archives/modemmanager-devel/2016-January/002595.html
>>> I got so into the habit of separating the pin verify and connect
>>> operations that forgot completely about that.  But the issue sounds
>>> similar.  Maybe it is a timing issue of some sort, which applies on any
>>> type of radio unlocking?
>>> Can you repeat the issue if you send the FCC auth command manually
>>> before enabling and connecting the modem?
>> I don't think that made any difference, not sure.
> Starting to think that it was just an arbitrary conincidence, and that
> the real problem is that the MBIM session is just "flaky".
> The good news is that I can reproduce the same problem on my MC7455 in
> MBIM mode.  The bad news is that I am still unable to correlate the
> problem to any specific input or configuration sequence. Sometimes the
> session is just "stuck", like many of you have reported for the EM7455.
> Connecting and all other MBIM management is fine.  But there is
> absolutely nothing coming back from the modem over the bulk endpoint.
> I tried resetting the modem and/or the USB link, and it ended up working
> again after a few attempts.  But I got a feeling that is just by pure
> chance.
> There must be some trick making it more reliable. But what could it be?

Didn't check yet myself, but this device does work reliably in Windows
in MBIM mode, right? I mean, Lenovo doesn't switch it to QMI in the
Windows driver they use, I assume?


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