Custom AT command support in ModemManager

[Aleksander Morgado]

Hey,

On Wed, Aug 16, 2017 at 1:36 AM, Jose, Shijo <Shijo.Jose at hughes.com> wrote:
> Moving thread (MBIM_CID_DEVICE_SERVICE_SUBSCRIBE_LIST support) form libmbim-devel list.
>

Thanks

>>> Is there way to send AT commands to the modem via MM?
>>>I tired -
>>> mmcli -m 0 --command="E0"
>>> error: command failed: 'GDBus.Error:org.freedesktop.ModemManager1.Error.Core.Connected: No AT port available to run command'
>
>> This happens when there is a single TTY and it is already connected, there is no other available channel to send commands. ModemManager doesn't setup CMUX automatically yet.
>
> Can this be manually enabled in M for MBIM devices?
>

I just realized you're working with a MBIM modem. So the "No AT port
available to run command" may actually mean there is no AT port
detected in the modem. Are you able to see a TTY listed in the
"System/ports" entry when you do "mmcli -m 0"?

>>> Also, can I have MM detect an already connected (plugged-in) USB modem, instead of waiting for a hotplug event?
>
>>If you're using my ModemManager openwrt integration setup, you should have a file in /var/run/modemmanager/events.cache which holds the MM-applicable events that >happened since the system was booted. If you run ModemManager yourself you should be able to start the daemon with the extra --initial-kernel-events=[PATH] argument >pointing to that file. Or, otherwise, see mm_report_events_from_cache() in /etc/modemmanager/modemmanager.common
>
> I don't see my device (cdc-wdm0) in this list when it is already plugged in when the host powers up. How is this list(events.cache) populated?
>

See:
https://bitbucket.org/aleksander0m/modemmanager-openwrt/src/8c553f2a1c090abf4da0f4e762ab6cec22d00557/modemmanager/files/25-modemmanager-net?at=master&fileviewer=file-view-default

Basically, we get "net" and "tty" hotplug events reported in OpenWRT;
for the net events we also check if there is a cdc-wdm device
associated to the network interface, and if there is one we
"mm_report_event" both the net and the cdc-wdm device. That
mm_report_event method is the one that appends entries to the
events.cache file (or removes them if we get a remove hotplug event).

-- 
Aleksander
https://aleksander.es