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

[Marcel Holtmann <marcel@holtmann.org>]

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Hi Guillaume,

> >>>>>>>> and what about the case when the SIM card is present, but PIN locked?
> >>>>>>>>
> >>>>>>>>> According to the result, it might be interesting to send ATI when the
> >>>>>>>>> constructor plugin is probe by oFono.
> >>>>>>>>> Thus with +GCAP info we can decide which driver to use.
> >>>>>>>> Is sending +GCAP after ATI really a standard? Have we tried anything
> >>>>>>>> else besides Huawei or ZTE?
> >>>>>>> I tried with more dongles from different vendors, as attached table.
> >>>>>>> The scenarios include:
> >>>>>>> With valid sim card, sim card PIN locked, no sim card, sim card locked.
> >>>>>>> N(ROM) in table indicates the SIM in ROM already.
> >>>>>>> ATI command can always return GCAP content in all tests.
> >>>>>> and what about other manufactures other than Huawei, ZTE and SpeedUp?
> >>>>>> What about Sierra, Ericsson etc.?
> >>>>> Just checked Dell 5530 with Ericsson module,
> >>>>> With SIM card or not, at+gcap can return +GCAP:+CGSM, +DS
> >>>>> But the ATI only returns: D5530
> >>>> I think it is clear that we need to do our homework here and properly
> >>>> document the different manufacturers. Someone sending patches for our
> >>>> doc/ directory?
> >>> There're many vendors of 3G dongle..
> >>> Huawei, ZTE (they share 70%+ of global market), Longcheer, Haier, Sentar, Viton, D-link, SCV, BandRich, Strongrising.. (more than 30 vendors in China)
> >>> Sierra, Sony-Ericsson, Option, Novatel, Alcatel, Samsung, LG, AnyData, C-motech, Micromax...
> >>> We can try with them step by step, but can we work out the 2 biggest firstly?
> >>> Looks ATI command can work for both Huawei and ZTE dongles.
> >>>
> >> I agree here, the work to be done over all manufacturers will be
> >> fastidious and might require a lot of dongles that we don't have currently.
> >> Maybe we could do as Ying An proposed as we are sure ATI works for
> >> Huawei and ZTE (at least the ones we have).
> >> However, conerning ZTE I haven't seen any CDMA dongle for the moment.
> >>
> >>>>>>>> Also you do realize that the GAtChat object and thus the file descriptor
> >>>>>>>> is owned by the modem plugin. The plugin itself is the only one that
> >>>>>>>> should do any kind of IO.
> >>>>>>>>
> >>>>>>>> So if we require to run ATI first to identify if we are GSM or CDMA,
> >>>>>>>> then this is a per modem manufacture specific detail. And we rather add
> >>>>>>>> a helper function like we did for CPIN polling that makes this easier.
> >>>>>>>>
> >>>>>>> In current code the 'driver' is hardcoded by comparing with vendor_list[].
> >>>>>>> So if it possible to break the step into several:
> >>>>>>> vendor_list[] in udevng just cares about vendor - by comparing vendor ID
> >>>> only,
> >>>>>>> and add all possible drivers according to that vendor - (for example add
> >>>>>>> WCDMA, CDMA2k, TDSCDMA, LTE ...drivers if Huawei dongle is plugged
> >>>> in),
> >>>>>>> and the probe interface in each driver does real probe work as to issue
> >>>>>>> ATI command to ensure only correct driver will be loaded?
> >>>>>> As I said before, the only time IO can be started is when the ->enable()
> >>>>>> callback of the modem plugin is called. Not a second earlier.
> >>>>> But if done after enable() called, from semantic aspect the correct driver has
> >>>> been
> >>>>> chosen. Indeed the probe() interface in each driver is not doing something to
> >>>> probe,
> >>>>> then can the work be done in probe()? As set CFUN=1 then doing some dongle
> >>>> vendor
> >>>>> specific work as query model or network mode by ATI, AT+GCAP command,
> >>>> etc..? After
> >>>>> that disable dongle when quit probe()?
> >>>> The probe() callback is for accepting the driver and allocating required
> >>>> local data structures. It is not for IO. And as you can see it has no
> >>>> callback handling like enable() with set_powered().
> >>>>
> >>>> As I said before, no AT commands before enable() has been called. That
> >>>> is how it is suppose to be. We are not changing this.
> >> First, ATI command is working without sending AT+CFUN=1, we could keep
> >> CFUN=1 into enable() as we do some vendor/modem type specific job there.
> >>
> >> Then vendor plugin can be chosen using udevng using Vendor ID, however
> >> driver type (CDMA/GSM) can't lie on the Product ID. So it will be hard
> >> to chose the right vendor plugin with right type.
> >> And if we can't send AT command before enable() time we will face to bag
> >> end e.g. :
> >> For huawei plugin we send GSM specific AT command (AT^RFSWITCH) during
> >> the enable() time.
> >> We are also querying the sim state using polling mechanism that might
> >> fail for CDMA modems that is not using SIM.
> >> What would you suggest here?
> > as I said before, no AT commands before ->enable() callback from the
> > core.
> >
> > The callback ->probe() is for accepting the modem driver binding and
> > allocating modem specific data memory. The callback ->remove() is for
> > cleanup.
> >
> > The callbacks ->enable(), ->disable() and ->set_online() are the only IO
> > entry points for every modem driver. And we need to keep it like this.
> 
> Ok, so I suggest to do the ATI at the very beginning of ->enable() callback.

the first command has to be always ATE0 +CMEE=1 since otherwise you a)
can not use the permissive syntax parser and b) your error values will
be useless.

But yes, after that it is fine to send ATI.

> Then depending on the ATI answer:
>      - tag the huawei modem data with GSM / CDMA type.
>      - send the GSM / CDMA specific AT commands followed by AT+CFUN=1.

What different commands depending on GSM or CDMA do you actually have?

The AT^RFSWITCH=? is exactly designed to handle if that command is
supported or not. There are plenty of GSM versions of the Huawei that do
not support AT^RFSWITCH. You do need to know if this is supported or
not.

Also we do not send AT+CFUN=1 in ->enable() callback. We bring the modem
into offline mode. The only time you send AT+CFUN=1 is if you have
hardware that does not support online/offline distinction. So if this is
true for Huawei CDMA modems, then the obvious questions is why that is
the case? Or is this a bug with our CDMA support not supporting offline
mode.

> We should not longer make the difference between "huawei" and 
> "huaweicdma" into udevng.
> It also means there is one unified plugin.

That is totally fine.

> > The callback ->pre_sim(), ->post_sim() and ->post_online() are the entry
> > points for selecting atom drivers. These are not allowed to do IO
> > directly either.
> 
> Here, using the tagged type, the plugin can decide which driver to use 
> to create atom.
> Does it sound ok to you?

Fine with me.

Regards

Marcel