Sierra EM7455 not recognized

[Tomek Mańko]

> "rfkill list" gives you the list of supported hardware and software
switches
> and their current state.

This is actually a funny thing I forgot to mention, but I do have a switch
that's labelled as `tpacpi_wwan_sw: Wireless WAN` which starts out
soft-blocked,
but unblocking it does nothing - no messages show up in `dmesg` nor `lsusb`
shows any new devices. It's kinds baffling how the rfkill is registered by
the
system but not the modem itself. And this probably means that the modem is
not
powered down in UEFI, since when I navigate to UEFI and disabled it there,
the
rfkill switch goes away.
So as far as `2) modem is powered off by the BIOS` is concerned, it's
probably
not the case (or at least not trivially so, maybe there's some secret
initialisation routine the Windows driver goes through?).

> make sure that there is no unknown devices showing up

Neither `lsusb` nor `usb-devices` seem to show any unrecognised devices:
https://gist.github.com/jaen/a53494848d10e58f0843410fe9543470

> the only way to make sure is to open up the laptop and see for
> yourself.

Well, I'd have to see what the guarantee terms and the employer say about
that.
Were it my laptop I wouldn't care, alas it is not so. Hopefully Lenovo does
not
have any restriction on opening the laptop for inspection.

> Or you could just check the state in the Windows installation, if you
> have one?

I tried a live USB Win 10 install and without drivers it didn't see anything
with Sierra's VID/PID. Installing the drivers didn't seem to help - even if
I
manually pointed towards modem's `*.inf` files it would install but say
that it
can't initialise the device or something to that effect. I suspect maybe it
might be doing something during system boot to initialise the modem and the
live CD doesn't retain anything across boot foling that.

There's another Lenovo at my workplace but with Windows installed, I'll try
to
see how it behaves there (though I tested it on an Arch pendrive before
Windows
drivers were installed and it didn't show up either) and I'll report back.

> or possibly 1199:9078 if in bootloader mode

That makes me think, don't I have to set something up specifically to feed
it
firmware? Windows drivers aparentlly containa a couple of provider-specific
firmware blobs (and one generic)>. I've read older Sierra Modems based on
Gobi 2000 chipset required that; maybe there's something similar that needs
to
be done? But then again, it doesn't even show up in bootloader mode, so I'm
not
sure how that even could be done.

If there's any other info I can provide feel free to let me know.

PS I don't really use MLs much, so I hopefully didn't break any netiquette.

On 26 June 2016 at 12:53, Bjørn Mork <bjorn at mork.no> wrote:

> Tomek Mańko <jaennirin at gmail.com> writes:
>
> > So my workplace bought some Lenovos L460 which are supposed to have
> Sierra
> > Wireless EM7455 modems built-in (and indeed it does have a sim slot on
> the
> > right side), but neither `lsusub` nor `usb-devices` seem to report any
> device
> > with VID/PID 1199:9079 this modem is supposed to have. Manually
> `modprobe`ing
> > WWAN-related drivers like `wcserial`, `cdc_wdm` or `cdc_mbim` doesn't
> cause any
> >  new device to be recognised (I have no `/dev/cdc-wdm`, `/dev/ttyACM` nor
> >  `/dev/ttyUSB` files and `dmesg` only reports the module loading
> message).
>
> I can think of only 3 explanations:
>  1) no modem installed
>  2) modem is powered off by the BIOS
>  3) modem does show up, but with a different VID/PID
>
> I am not sure how Lenovo connects stuff nowadays, but wrt 2) you should
> check the status of any radio kill switch.  "rfkill list" gives you the
> list of supported hardware and software switches and their current
> state.
>
> As for 3), make sure that there is no unknown devices showing up.  You
> should be able to figure out what they all are (hubs, camera, bluetooth,
> fingerprint reader, etc). In theory your Lenovo EM7455 should only show
> up as 1199:9079 (or possibly 1199:9078 if in bootloader mode), but maybe
> you got some other modem? You cannot always trust what you're told by
> resellers, unfortunately. And Lenovo provides a choice of different
> modems AFAIK.
>
> Wrt 1), the only way to make sure is to open up the laptop and see for
> yourself.  This is usually pretty easy with Lenovo laptops.  If you
> Google around you'll probably find the hardware maintenance manual,
> telling you exactly where to find the modem m.2 socket.
>
> Or you could just check the state in the Windows installation, if you
> have one?
>
>
> Bjørn
>
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