Quectel EC21, Debian Jessie, kernel 4.4 (patched)

[Aleksander Morgado]

On Fri, Aug 31, 2018 at 9:24 AM, Brendan Simon (SEPL)
<brendan at successful.com.au> wrote:
> I have a embedded linux system, which has been used with a Quectel UC20
> device without any issues, but moving to the Quectel EC21 is proving
> problematic.
>
> Setup is:
>
> Zynq 7000 ARM SOC
> EC21 dev-kit (connected via USB)
> Analog Devices linux kernel 4.4 -- monkey patched for EC21 using:
>
> https://www.quectel.com/UploadImage/Downlad/Quectel_WCDMA&LTE_Linux_USB_Driver_User_Guide_V1.8.pdf
>
> Debian Jessie (8.10)
> ii  modemmanager     1.4.0-1     armhf
> ii  network-manager  0.9.10.0-7  armhf
>
>
> After the patches were applied, the device is recognise on the USB bus and
> MM also recongises the modem.  However I'm getting a failed status of SIM
> not found ("sim-missing"), but the SIM is present the dev-kit is known to
> work using a Windows box (i.e. gets an IP address from the 4G service).
>
> In linux, after power up, MM shows the "sim-missing" failure reason.
>

I believe that is just because you're using an ancient modemmanager
version, and the new "UIM" support isn't implemented in MM 1.4.0.
Could you update to MM 1.8? It will be totally compatible API-wise.

> Interestingly, after I press the reset button on the dev-kit, MM recognises
> a new modem and shows a "registered" status.
>
> I system now recognises the modem (/dev/cdc-wdm0 is registered as well as
> some /dev/ttyUSB* devices).
>
> However, nmcli shows the device as a ttyUSB instead of cdc-wdm0 !!  Looking
> at mmcli outupt, it seems the "primary port" changes from "cdc-wdm0" to
> "ttyUSB8".
>
> Is this normal?  Can I force it to only use cdc-wdm?
>

That may be because the QMI port isn't responding timely after the
reset. Again, I believe this would be solved with newer MM/libqmi.


> Why does the SIM get recognised after pressing the reset button and using
> the ttyUSB interface, and not recongised after powerup and using the
> cdc-wdm0 interface?
>
> I also tried connecting the dev-kit to a Debian 9 VM, but I couldn't get MM
> to recognise it at all.  The ttyUSB and cdc-wdm0 interfaces were present,
> but "mmcli -L" shows nothing ("No modems found")
>
> Could this be related or is it a different problem altogether?
>
> How can I get MM to recognise the modem in the Debian 9 setup?
>
> linux kernel     4.9.65-3
> modemmanager     1.6.4-1
> network-manager  1.6.2-3
>

This may also be due to timing in the QMI port when it boots, maybe
we're not waiting enough. I'd suggest you try with the latest MM 1.8
if possible.

-- 
Aleksander
https://aleksander.es