Sierra Wireless EM7455

[Dan Williams]

On Thu, 2016-06-09 at 18:03 +0200, Ralph Plawetzki wrote:
> Am 09.06.2016 um 17:09 schrieb Dan Williams:
> > 
> > QMI and MBIM are just different ways to talk to the modem's
> > firmware.
> >  Like languages.  QMI is proprietary to Qualcomm, older than MBIM,
> > and
> > ties much more closely to the firmware architecture of Qualcomm
> > chips.
> > 
> > MBIM is a "standard" protocol that is used by many vendors, and is
> > built-in to Windows 8 and later, so if a modem supports MBIM then
> > it
> > doesn't need special drivers in Windows.  It's supported by many
> > vendors, regardless of what chips are in their modems.
> > 
> > To make it easier to integrate into Windows, Qualcomm provided
> > firmware
> > to modem vendors that use their chips that speaks the MBIM
> > protocol.
> >  Some vendors choose to use it by default.  Some vendors also allow
> > special commands to switch Qualcomm firmware between speaking QMI
> > and
> > MBIM by default.  This is what the Sierra tool that Bjorn is
> > talking
> > about does.
> This is indeed very interesting. I googled a while but was not able
> to
> find much about this topic. And none of it was that compact. Thank
> you!
> 
> > 
> > Only newer Sierra devices based on Qualcomm chips need this
> > command.
> >  Other vendors like Huawei, Novatel, ZTE, etc don't appear to need
> > this
> > QMI command, even if they use Qualcomm chips inside.  Not sure why
> > Sierra is doing this, but they appear to be the only ones so far.
> Ok. I thought it might be this way.
> 
> > 
> > If the modem's usb vendor ID is a Lenovo vendor ID, then it's a
> > Lenovo
> > customized Sierra-produced modem.  Vendors like Lenovo and HP do
> > this
> > to ensure that only approved modems are used in their own machines,
> > technically to ensure that the modem and antenna solution are
> > paired
> > together.  This is theoretically for regulatory approval, since the
> > modem *and* antenna are certified together, not just the modem
> > itself.
> >  Antenna can have a big effect on how the modem performs and
> > whether it
> > meets regulator requirements.  The cynical among us will say this
> > is
> > actually to ensure that users have to pay HP money for a modem
> > instead
> > of getting them on the secondary market though.
> I see. I am not sure whether it says 'Lenovo' or 'Sierra' on lsusb.

Sierra's vendor id is 1199.  If your device (as reported by lsusb) is
not 1199, then it's a OEM-ized device and probably subject to the BIOS
lock that I explained in the previous mail.

Dan