Re: [PATCH] doc: Add modem Type property

[Lei Yu <lei.2.yu@nokia.com>]

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Hi Denis,

On 01/21/2011 02:04 PM, ext Denis Kenzior wrote:
> Hi Lei,
>
> On 01/21/2011 03:48 PM, Lei Yu wrote:
>> Hi Denis,
>>
>> On 01/21/2011 01:04 PM, ext Denis Kenzior wrote:
>>> Hi Lei,
>>>
>>>>>> +        string Type [readonly, optional, experimental]
>>>>>> +
>>>>>> +            String representing the type of the modem device.
>>>>>> +
>>>>>> +            The possible values are:
>>>>>> +                "gsm"     Modem supports one or more of the 3GPP
>>>>>> +                    family of technologies including GSM,
>>>>>> +                    EDGE, UMTS, HSPA, LTE.
>>>>>> +                "cdma"  Modem supports one or more of the 3GPP2
>>>>>> +                    family of technologies including CDMA 1x,
>>>>>> +                    EVDO.
>>>>>> +                "hfp"    Bluetooth hands-free profile (HFP) modem
>>>>>> +
>>>>>
>>>>> So one pointed question:
>>>>>
>>>>> How are we planning to support dual-mode devices with this property?  I
>>>>> believe during the CDMA workshop we decided that the clients should
>>>>> simply look at the set of interfaces, not a semi-static property...
>>>>
>>>> We understand that the decision during the CDMA workshop but as we
>>>> explained one use case in the cover letter
>>>> (http://lists.ofono.org/pipermail/ofono/2011-January/007890.html) for
>>>> this RFC, there will be cases where atom's D-Bus I/F is not suitable (or
>>>> as a reliable way) for telling what is current mode (CDMA or GSM). E.g.,
>>>> in the case of retrieving serial number from modem. Currently both CDMA
>>>> and GSM shares the same I/F (ofono.org.modem) rather than having
>>>> separate (ofono.org.cdma.modem). And, further if no other atom has been
>>>> instantiated, then, there will be no other way to tell which mode (CDMA
>>>> or GSM) the modem is. And, further for displaying serial number, upper
>>>> layer will need to know it is CDMA or GSM. In case of CDMA, the serial
>>>> number is MEID and GSM it is IMEI. As explained in cover letter, we
>>>> anticipate more cases like this.
>>>
>>> So let us say I have a dual-mode modem.  Are there now two serial
>>> numbers? One for MEID and one for IMEI?  Are there now two
>>> Manufacturers? Two Revisions?
>>
>> Try to clarify what you try to ask first. Let's start with the dual-mode
>> case where the modem is integrated modem (one piece of HW) where it
>> supports both CDMA and GSM. Then, there is case where the phone actually
>> has both MEID and IMEI. And, these two numbers are actually the same
>> (note, per IMEI's assignment there is a pre-arranged segment for this
>> kind of world phone). And, in which case, one manufacture, one revision.
>> Per the other thread, in which case the "Type" will be something like
>> "gsm_cdma".
>
> So how does the modem type help you here if you have 'gsm_cdma'?  Is the
> modem giving you a MEID? An IMEI?  I'm not convinced the Type helps you
> in any way.  It might help you for HFP, but certainly not the dual mode
> case.
>

First, our original use case is really for a single mode case, not dual 
mode. Please see our cover letter in our original RFC. Please do let us 
know if you agree or disagree whether there is a problem needing to be 
solved for single mode case.
Second, in case of the example I gave above, modem will provide one 
serial number which is both MEID and IMEI since they are identical. In 
which case based on "Type" setting to "cdma_gsm", it will be upper 
layer's choice to do the processing. E.g., upper layer can do something 
like: MEID/IMEI: xxxxxxx.

>> Of course, there can be case where two physical modems are in the device
>> in which case there will be two separate serial numbers and two
>> manufacturers and revisions. I am assuming you are not asking for this
>> case.
>
> Yes, I'm ignoring the true dual-mode dual-radio case right now.
>
> Regards,
> -Denis

Regards,
-Lei