[PATCH 2/3] telit: add support for Dell VID in Telit plugin

[Daniele Palmas]

Hi Aleksander,

2016-04-27 21:41 GMT+02:00 Daniele Palmas <dnlplm at gmail.com>:
> Hi Aleksander,
>
> 2016-04-27 21:20 GMT+02:00 Aleksander Morgado <aleksander at aleksander.es>:
>> On Wed, Apr 27, 2016 at 9:04 PM, Aleksander Morgado
>> <aleksander at aleksander.es> wrote:
>>> On Wed, Apr 27, 2016 at 4:36 PM, Daniele Palmas <dnlplm at gmail.com> wrote:
>>>> This patch adds support for Dell VID in Telit plugin in order to provide
>>>> Dell branded Telit modems support
>>>> ---
>>>
>>> No, we don't want to do that.
>>>
>>> We now have a "Dell" plugin for 1.6.x in git master; this plugin has
>>> the VID based filter, and what it does is detect which kind of modem
>>> it is (QMI, MBIM, Ericsson, Novatel or Sierra). What we should do is
>>> to treat the Telit support in the Dell plugin as we do for Sierra and
>>> Novatel. Please check the Dell plugin to see how that goes (basically
>>> just parsing GMI/CGMI output to match the real vendor) :)
>>
>> One of the rationales for this is to try to minimize the amount of
>> changes required in the different plugins when new Dell-branded
>> devices appear (we don't want to require new commits for each new
>> modem VID/PID appearing in the wild). The Dell plugin should be
>> intelligent enough to decide which manufacturer is really behind the
>> device. In your case, you could just get the Dell plugin run the Telit
>> plugin's custom init and create a MMBroadbandModemTelit afterwards.
>> Maybe there's something that I'm not considering which prevents this
>> from being possible?
>
> I agree with you and I already have a patch that adds support for this
> modem in Dell plugin: it just needs a bit of refactoring for Telit
> plugin to export some functions, but I don't think this is a problem.
>
> The real problem is that Dell plugin has poor probing performance with
> a modem like HE910 that has 6 ttyACM ports, only two of which answers
> to AT commands: there are three different commands (+GMI, +CGMI,
> I1I2I3) that should be retried three times, since the ports are not
> answering.
>
> This means that the modem with Dell plugin is available after more
> than 60 seconds, while with Telit one after about 10 seconds.
>
> Is there a way to speed up port probing in Dell plugin without
> changing it too much? I don't want to introduce regressions for other
> Dell modems.
>
> Thanks,
> Daniele
>

Taking a deeper look at Dell plugin, my idea is to use the same udev
tag needed for Telit dynamic port configuration
(ID_MM_TELIT_PORTS_TAGGED) to set cgmi_retries and ati_retries to 0,
since Telit modems always answer to +GMI.

In this way port probing time should be reduced and the other modems
not affected by the change.

I will submit another patchset for adding support in Dell plugin.

Thanks,
Daniele


>>
>> --
>> Aleksander
>> https://aleksander.es