Re: [MM] [PATCH 2/5] novatel: Use the ALLOWED_SINGLE_AT property. Saves 5 seconds on probing.

[Dan Williams <dcbw redhat com>]

On Wed, 2012-05-02 at 19:16 +0200, Bjørn Mork wrote:
> Nathan Williams <njw google com> writes:
> > On Wed, May 2, 2012 at 6:11 AM, Aleksander Morgado <aleksander lanedo com>wrote:
> >
> >> On 05/01/2012 06:07 PM, Nathan Williams wrote:
> >> > Date: Thu, 22 Mar 2012 16:18:24 -0400
> >> > Subject: [PATCH 2/5] novatel: Use the ALLOWED_SINGLE_AT property. Saves 5
> >> >  seconds on probing.
> >>
> >> Is it that the modem exposes only one AT port? Or that it exposes
> >> multiple ports but only one is needed? The property was meant for the
> >> former case only, not for the latter.
> >
> >
> > With this modem only one of the four exposed serial ports is an AT port. I
> > believe the remaining ones are two Qualcomm things and GPS.
> 
> That sounds very likely.  A wild guess based on similar devices is that
> the four ports are AT, QCDM, NMEA and QMI.  You could try writing
> $GPS_START to the suspected NMEA port and see if that enables output
> from the GPS.  QCDM could be tested using the tests in libqcdm (included
> with ModemManager).
> 
> Testing for a QMI port is currenly non-trivial. You will have to modify
> the cdc-wdm or qmi_wwan drivers to bind to the device and see if it
> replies to QMI.  A nice test util for someone to write (I've been
> planning to, but haven't had the time and probably won't either...)
> would be something using libusb to send a CDC embedded QMI message (the
> subsystem version check looks like a good candidate) to a given
> device/interface.  Should be fairly easy to write.

Port layout of the Novatel 551L (LTE Band 13 device similar to the E362
this Nathan's plugin targets, but USB instead of PCI-E minicard) is as
follows:

0: AT commands
1: DM
2: another DM
3: unknown (probably QMI; doesn't respond to $GPS_START)
4/5: CDC Ether

Odd that we have two DM ports.  If Intf3 is really QMI then we should
make sure it's blacklisted in 'option' so we don't have to do
serial-related junk with it.

Dan