Huawei E3131 and the ignored at^ndisdup command

[Ben Chan]

On Sun, Jun 30, 2013 at 11:22 PM, Aleksander Morgado
<aleksander at lanedo.com> wrote:
> On 30/06/13 14:59, Enrico Mioso wrote:
>> Hello guys!
>> I'm happy to be now a member of this list! I read some messages in the
>> archives and understood that I _should_ subscribe! :)
>>
>
> Yes, thanks for doing that :)
>
>> I have an Huawei E3131 device - it reuses the E398 ID, and similar
>> disfunctions.
>> First of all - this hardware version doesn't support LTE, and has been
>> boughton Italy. the "ati" commands reports:
>> Manufacturer: huawei
>> Model: E3131
>> Revision: 21.157.41.01.1037
>> +GCAP: +CGSM,+DS,+ES
>>
>>
>> at^hwver says:
>> ^HWVER:"CH2E303SM"
>> at^vertime says:
>> ^VERTIME:Apr 19 2012 15:16:47
>>
>> So it seems a pretty recent firmware version.
>> As you know for sure, the device actually has the same ID as the E398,
>> see attached lsusb; and is handled by the option driver (for the serial
>> ports) and the cdc_ncm driver (for the wwan interface).
>>
>> Even in this case, the commands:
>> at^ndisdup
>> or
>> at^ndisconn
>> returns an "OK" message, but the modem will not ever try to connect to
>> the network.
>> ModemManager, in a debug session, ended up using the 2plain ppp
>> connection".
>> I wanted to inform you all about the fact that:
>> - I have the device
>> - I can help in testing
>>
>> And hoping someone has some ideas about this.
>>
>> thank you all for your help!
>
>
> According to Huawei, the only modems supporting NDISDUP in a Linux-based
> system are those exposing a standard ECM/NCM interface, i.e. with the
> following setup:
>  * bInterfaceClass=02
>  * bInterfaceSubclass=06
>  * bInterfaceProtocol=00
> or
>  * bInterfaceClass=02
>  * bInterfaceSubclass=0d
>  * bInterfaceProtocol=00
>
> In these modems, dialling is done through NDISDUP in the AT (PCUI) port.
>
> Other modems exposing a wwan interface but without those
> class/subclass/protocol values are supposed to support NDISDUP through
> the NCM port with endpoint 0, but that is unsupported for now. There are
> also newer Huawei modems labelled as 'hi-link' (like the E303), which
> are supposedly auto-configured, but I haven't played with these yet. So
> for now, NDISDUP is used in those modems that we know for sure it is
> supported.
>
> In short, having the NDISDUP command supported by the AT interpreter in
> the modem doesn't mean it will actually do anything with it.
>
>

I notice that the following upstream cdc_ncm patches (since kernel
3.8) expose a wwan0 interface for certain Huawei modems with a
non-standard NCM interface. But according to
77-mm-huawei-net-port-types.rules, they use PPP to dial up. Has anyone
tried making use of the wwan interface?

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=bbc8d9228ea8e37ce29fa96150d10b85a2c7be60
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=96316c595697ae9a2a90badd6f00035f2f384773
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=1f84eab4ad73bcb7d779cba65291fe62909e373f