Re: ATModem-PPP Doubts

[Denis Kenzior <denkenz@gmail.com>]

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Hi Arun,

> Hi,
> 
> We using a modem through atmodem interface. While testing the
> functionalities, we found that the dataconnectionmanager interface is not
> coming up.
> 
> We enabled the gprs modem driver creation and context creation in by adding
> it in atgen.c
> 
> atgen_post_sim(struct ofono_modem *modem)
> {
> ---------------------------------------------------------------
> ---------------------------------------------------------------
> gprs = ofono_gprs_create(modem,0, "atmodem", chat);
> gc = ofono_gprs_context_create(modem, 0, "atmodem", chat);
> 
> if (gprs && gc)
>         ofono_gprs_add_context(gprs, gc);
> 
> mw = ofono_message_waiting_create(modem);
> if (mw)
>         ofono_message_waiting_register(mw);
> 
> }
> After this change the dataconnection manager interface was shown in the
> ./list-medem script.
> 
> 1) Is this a correct change ? why was this not present in atgen? Could any
> one clarify?

The change is correct.  Our ppp support is still experimental, so probably no 
one got around to enabling this in atgen.  Patches welcome.

> 
> 
> We wanted PDP context activation through atmodem and we could see that our
> modem returns
> *at+cgdcont=?
> +CGDCONT: (1-255),("IP","IPV6"),,,(0),(0,1,2)
> 
> OK
> *
> where as Nokia modem (E63) returns
> 
> *at+cgdcont=?
> +CGDCONT: (1-2),"IP",,,(0),(0)
> +CGDCONT: (1-2),"IPV6",,,(0),(0)
> 
> OK
> *
> The modem we use is returning the string in a different way from 3GPP
>  27.007 , which says to return the multiple PDP types are separate lines.

Correct, we tend to go by the book.  This is one of the areas where atgen is 
useful; it tells you quite quickly where your modem is compliant / not 
compliant with 27.007.

> 
> We modified the Gprs.c file in atmodem driver, to search for the list of
> strings, and we are able to make PDP context activation.
> 
> 2) Is this change an accepted one?

Depends on how you did it.  In general there are three acceptable ways:

- Accept both compliant and non-compliant format if possible while maintaining 
a high level of strictness.
- If the above is not feasible, quirk the functionality by sending a 
OFONO_VENDOR_* flag to the atom driver and writing the necessary quirk handling 
code there.  This requires a proper modem driver as atgen does not use quirks.
- If both of the above are too invasive, then writing your own atom driver & 
modem driver is an option

Sounds like option 1 or 2 is likely the case for you.

> 
> 3) Currently i am stuck at the PPP (IPCP stage), how can i link this
>  context (and PPP link) to my Ubuntu's network manager?

I assume you're not failing to negotiate the IPCP parameters, otherwise we'd 
like to see a log of gsmdial with pppdump option enabled for your modem.

Monitor ofono's PrimaryContext interface of the context you're activating.  It 
will send you all the details of the ppp connection, including net interface, 
ip, and dns information.  

Integrating this into NetworkManager is left as an exercise to the reader :)  

Regards,
-Denis