[Pkg-utopia-maintainers] Bug#828820: Dell DW5811e should be working with the latest MM and supporting packages

[Bjørn Mork]

Luc Bégault <luc at begault.net> writes:

> here is the output of:
> # mmcli -m /org/freedesktop/ModemManager1/Modem/0
>
> /org/freedesktop/ModemManager1/Modem/0 (device id
> 'abcc5d4e7daab7bd404d58f7ca9c6e799fe47155')
>   -------------------------
>   Hardware |   manufacturer: 'Dell'
>            |          model: 'MBIM [413C:81B6]'
>            |       revision: 'SWI9X30C_02.05.07.00'
>            |      supported: 'gsm-umts, lte'
>            |        current: 'gsm-umts, lte'
>            |   equipment id: '353991070070340'
>   -------------------------
>   System   |         device:
> '/sys/devices/pci0000:00/0000:00:14.0/usb2/2-2'
>            |        drivers: 'cdc_mbim'
>            |         plugin: 'Dell'
>            |   primary port: 'cdc-wdm0'
>            |          ports: 'cdc-wdm0 (mbim), wwp0s20f0u2i12 (net)'
>   -------------------------
>   Numbers  |           own : 'unknown'
>   -------------------------
>   Status   |           lock: 'none'
>            | unlock retries: 'sim-pin2 (3)'
>            |          state: 'registered'
>            |    power state: 'on'
>            |    access tech: 'lte'
>            | signal quality: '29' (cached)


Great! Now we know that
 - the modem is using the cdc_mbim driver,
 - the SIM is unlocked,
 - the radio is on, and
 - the modem is registered in the LTE network

That's really good so far.

> Since new version of modemmanager, the modem is detected and my
> connection is avaible in network manager. But when I try to connect, I
> have:
> #nmcli c up SFR
> Error: Connection activation failed.
>
> #nmcli device show
> ../..
> GENERAL.DEVICE:                         cdc-wdm0
> GENERAL.TYPE:                           gsm
> GENERAL.HWADDR:                         (unknown)
> GENERAL.MTU:                            0
> GENERAL.STATE:                          30 (disconnected)
> GENERAL.CONNECTION:                     --
> GENERAL.CON-PATH:                       --
> ../..
>
> Maybe I should report now to networkmanager ?

No.  This is most likely a failure related to MM. I don't think it's
necessarily a bug, though... More likely something related to your
connection.  Let's take a closer look at it.

Try to collect the MM debug logs and see if it provides more hints:

 systemctl stop ModemManager
 /usr/sbin/ModemManager --debug
 nmcli c up SFR


This should print lots of details of what MM is doing and how if fails.
It can also be useful to rerun the "mmcli -m .." command after the
connection attempt, note the number of the created "bearer" object, and
then run "mmcli -b X" with this number to inspect it.


Just one additional warning for later when you are able to connect (or
for anyone else reading this and stopping at the next step): You will
need a kernel update to consistently get IP packets through. There is an
odd timing issue in the firmware of these modems, which sometimes cause
a silent failure if the driver probe is "too fast".  The workaround for
this issue is present in kernels v4.7 and later, and also in stable
kernels v4.6.5 and later. I believe the first Debian kernel package
version with this fix will be the soon upcoming "4.7.2-1"


Bjørn