Re: [RFC PATCH v3] gprs: add function to handle activated context

[Arun Ravindran <ext-arun.1.ravindran@nokia.com>]

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Hi Redouane,

>>> the network. The mobile sends a piggybacked
>>> PDN CONNECTIVITY REQUEST with the initial attach request in order to
>>> initiate the initial EPS context.
>>>
>> How does this happen from oFono (or in the TE-MT Interface).
> The problem is, the initial EPS context is initiated by mobile, not by
> It's triggered by AT+CGATT=1 (or AT+CFUN=1 if we have auto attach enabled).
>> Does it mean that in for EPS context the TE will have to do the same
>> steps what it does for GPRS?
> For the EPS context (non initial) yes.
>
> For the initial EPS context we don't use AT+CGACT and CGDCONT.
>> the PDN CONNECTIVITY REQUEST has the APN name, and for TE, CGDCONT to
>> set the APN is called with a context id, in that case what is the need
>> for the cid handling done in this patch?
>  From 24.301:
>
> In order to request connectivity to a PDN using the default APN, the UE includes the Access point name IE in the PDN CONNECTIVITY REQUEST message or, when applicable, in the ESM INFORMATION RESPONSE message, according to the following conditions:
> -    if use of a PDN using the default APN requires PAP/CHAP, then the UE should include the Access point name IE; and
> -    in all other conditions, the UE need not include the Access point name IE.
> ----
>
> For the initial EPS context the UE may have to provide the APN in some cases. From 27007 we don't have an at command such as AT+CGCONT to specify the parameter that'll be used for the initial EPS context (like APN).
>
> Regarding the patch, In 3G when you get the following unsolicited  "ME PDN ACT X" (where X is the CID, see +CGEREP) it's because you activated a context (AT+CGACT).
> In this case you already specified the CID with AT+CDCONT before AT+CGACT.
>
> In LTE you can get this event in two cases; after the attach procedure (AT+CGATT) and in this case you don't know the CID before, or after AT+CGDCONT and AT+CGACT as in 3G.
>

So the spec says, ME PDN ACT can come even for an implicit context 
activation request associated with CGATT, which is the case with EPS.

For 3G, if this happens (ME PDN ACT) for UE initiated activation of 
context, then the cid is already set with CGDCONT.

For EPS this can happen for default context, where cid is not set with 
CGDCONT, but is in the range as returned by CGDCONT.

Here the cid issue, because cid is managed by ofono and is never 
communicated to modem.  Probably to avoid sending too many CGDCONT's 
during startup. or is it something else?

I thought the default context activation will come to TE as NW ACT, with 
a cid not in range of CGDCONT.


regards
Arun