Re: The way to install proper driver for 3G dongle in oFono

[Marcel Holtmann <marcel@holtmann.org>]

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Hi Guillaume,

> >> We are facing a problem in oFono when using 3G modems:
> >>
> >> A CDMA2000 modem can have same PID with WCDMA modem, or TDS-CDMA 
> >> modem -- 3G modem vendors already confirm they do that.
> >>
> >> That's to say, if following current strategy, it will be a problem to 
> >> install proper driver for this kind of 3G modem.
> >>
> >> So, is it feasible to find out a solution such as to probe the modem 
> >> firstly, find out what kind of network modes it supports, and then 
> >> install the driver?
> >>
> >> The way to probe the modem could be some action as to read the 
> >> capability or get system mode, or issue some specific AT command that 
> >> only response to certain network mode?
> >>
> >
> > Indeed, we could use for Huawei modems for instance the AT^SYSINFO 
> > command and retrieve the sys_mode field and parse it, I have found 
> > this in public Huawei specifications:
> >
> > <sys_mode>: System mode. The values are as follows:
> > 0 No service.
> > 1 AMPS mode
> > 2 CDMA mode
> > 3 GSM/GPRS mode
> > 4 HDR mode
> > 5 WCDMA mode
> > 8 CDMA/HDR HYBRID mode
> >
> > Thus we can chose accordingly the drivers to create oFono atoms.
> 
> After some investigations, it seems SYSINFO won't be enough to get the 
> modem type because with this AT command we will have to be registered to 
> the network to get the system mode.
> The only way I found until now is using the AT+GCAP to check whether the 
> modem is CDMA or GSM type.
> However if we do the AT+GCAP request for each constructor plugin 
> (huawei, zte, ...) it will bring some duplicated code.
> Does someone see any better solution?

I like to see that we do proper homework here. The first question is
actually can you execute AT+GCAP if not SIM card has been inserted or is
actually locked? And if not does, ATI provide an extra +GCAP response.
Without a SIM atom you will not be able to unlock the modem. And you can
only create the SIM atom if you know what modem technology you are
using. Additionally of course additionally, what are the responses for
various modem models and manufactures. Are they doing this actually
properly.

We need OFONO_AT_DEBUG traces for all the various permutations of this
behavior. This needs to be documented first. Feel free to send patches
to add the results to doc/ directory inside oFono.

Just randomly hacking around will get us in trouble and will make well
behaved modems like MBM or IFX fail or suffer for no apparent reasons.

Regards

Marcel