Anyone testing an MC7430 or other MDM9x30 based modem

[Bjørn Mork]

Bjørn Mork <bjorn at mork.no> writes:

> Luckily, waking up is abstracted nicely away in qmi_wwan_manage_power,
> so adding this is a piece-of-cake. The only thing that worries me is
> whether we can do this unconditionally, or if we have to make it
> per-device. I'll test with all the QMI devices I have and see what
> happens.  I really like the fact that there is so little device specific
> in the current driver.  It makes it so much easier to add new devices,
> both dynamically and by patching.  No need to figure out chipset or
> firmware version first.
>
> Well, if it works then it works.  I'll just have to test for a while.

The good news is that none of the QMI devices I have seem to object to
this control message.  They all return successfully.  Tested on

 Huawei E392
 Huawei E367
 HP un2420 (Gobi 2000)
 Sierra Wireless EM7305
 Sierra Wireless MC7710

 and of course the Sierra Wireless MC7455.

The fact that it works on the very old un2420 is encouraging. So I'm for
enabling this unconditionally, unless there are objections?

The bad news is that this isn't entirely enough.  We also need some
cooperation with userspace, i.e. libqmi.  There appears to be a
significant delay between sending the control request and the firmware
actually accepting QMI requests.  One possible workaround is simply
keeping the device node open.  I guess that will work fine for
ModemManager. But not for qmicli...  I am currently cheating by doing
cat >/dev/cdc-wdm2 in another terminal.  But this will need a better
solution.

I do see Sync indications from the modem when I test this, and I assume
those are indications supposed to tell the application that the modem is
ready for requests.  So it might be as simple as wating for one of those
before sending requests.  Except that we dont' know when to wait and
when not to...

And in the good and bad news category:  The EM7305 made my laptop oops
with v4.4-rc2.  This turned out to be due to a recent change in
cdc_ncm.  I guess it's a good thing that I had a reason to test one of
those modems before v4.4 was released.  Although it always is a bit
frustrating to hit those kind of things when you are testing something
else ;-)


Bjørn