[ltp] RE: Verifying Linux compatibiliy for the LTE modems in the 2nd gen
X1 Carbon
Peter FP Zhang
linux-thinkpad@linux-thinkpad.org
Thu, 6 Mar 2014 01:59:10 -0800 (PST)
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Hi Bj=C3=B8rn,
You answered my question too. :)
Long time ago I was ever eager to know why PC Linux can not recompile Andri=
od drivers of 3G/LTE directly. Thanks for your details about the interface =
difference.
From: Bj=C3=B8rn Mork [via Linux Thinkpad] [mailto:ml-node+s10952n21035h71@=
n7.nabble.com]
Sent: Wednesday, March 05, 2014 10:33 PM
To: Peter FP1 Zhang
Subject: Re: Verifying Linux compatibiliy for the LTE modems in the 2nd gen=
X1 Carbon
James Knott <[hidden email]</user/SendEmail.jtp?type=3Dnode&node=3D21035&i=
=3D0>> writes:
> Bj=C3=B8rn Mork wrote:
>> Perfectly understandable. I'm not going to claim that there are many
>> Linux users who care about 3G & LTE, so I'm not surprised that no big
>> customers require it. Just judging by looking at my co-workers, who
>> mostly use Thinkpads with 3G modules and have free mobile broadband, I
>> do not see many real users. But there are some, including some Linux
>> users.
>
> One thing to bear in mind is that Android tablets & phones support 3G &
> LTE and Android is built on Linux, so the drivers are out there, somewher=
e.
Well, although both chips and the kernel is mostly the same, the
interfaces between them are actually quite different. Laptop modems
interface to the host via USB (even if the physical slot is m.2 or
mini-PCIe), while the Android devices usually have a shared memory
interface between modem and host. This makes the drivers pretty
different. So you can't just take an Android driver and use it on a
laptop, even if the LTE chip is e.g. a Qualcomm MDM9200 or Intel XMM7160
in both systems.
But mobile broadband USB modems designed for Windows8 systems have to
support the CDC MBIM class. And we do have a class driver for that in
Linux. So in theory, the modems should all just work out of the box.
In practice we may have to change a few minor things though. For
example, to support the MDM9200 based Sierra Wireless MC7710 we had to
allow a CDC MBIM function with no CDC Union descriptor (required by the
spec, but obviously not by Microsoft and therefore "forgotten" by
Sierra). And we also had to make the driver terminate all transfers
with a short packet, even though the spec allows dropping the Zero
Length Packet on maximum length transfers.
Bj=C3=B8rn
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If you meet any Linux compatibility issues on ThinkPads, please try to ping=
me, I will check if there is anything I can help.
--
View this message in context: http://linux-thinkpad.10952.n7.nabble.com/Ver=
ifying-Linux-compatibiliy-for-the-LTE-modems-in-the-2nd-gen-X1-Carbon-tp210=
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<p class=3D"MsoNormal"><span lang=3D"EN-US">Hi Bj=C3=B8rn,<o:p></o:p></span=
></p>
<p class=3D"MsoNormal"><span lang=3D"EN-US" style=3D"font-size:10.5pt;font-=
family:"Calibri","sans-serif";color:#1F497D"><o:p> =
;</o:p></span></p>
<p class=3D"MsoNormal"><span lang=3D"EN-US" style=3D"font-size:10.5pt;font-=
family:"Calibri","sans-serif";color:#1F497D">You answer=
ed my question too. :)<o:p></o:p></span></p>
<p class=3D"MsoNormal"><span lang=3D"EN-US" style=3D"font-size:10.5pt;font-=
family:"Calibri","sans-serif";color:#1F497D">Long time =
ago I was ever eager to know why PC Linux can not recompile Andriod drivers=
of 3G/LTE directly. Thanks for your details about the interface
difference.<o:p></o:p></span></p>
<p class=3D"MsoNormal"><span lang=3D"EN-US" style=3D"font-size:10.5pt;font-=
family:"Calibri","sans-serif";color:#1F497D"><o:p> =
;</o:p></span></p>
<p class=3D"MsoNormal"><b><span lang=3D"EN-US" style=3D"font-size:10.0pt;fo=
nt-family:"Tahoma","sans-serif"">From:</span></b><span =
lang=3D"EN-US" style=3D"font-size:10.0pt;font-family:"Tahoma",&qu=
ot;sans-serif""> Bj=C3=B8rn Mork [via Linux Thinkpad] [mailto:ml-node&=
#43;<a href=3D"/user/SendEmail.jtp?type=3Dnode&node=3D21044&i=3D0" target=
=3D"_top" rel=3D"nofollow" link=3D"external">[hidden email]</a>]
<br>
<b>Sent:</b> Wednesday, March 05, 2014 10:33 PM<br>
<b>To:</b> Peter FP1 Zhang<br>
<b>Subject:</b> Re: Verifying Linux compatibiliy for the LTE modems in the =
2nd gen X1 Carbon<o:p></o:p></span></p>
<p class=3D"MsoNormal"><span lang=3D"EN-US"><o:p> </o:p></span></p>
<p class=3D"MsoNormal"><span lang=3D"EN-US">James Knott <<a href=3D"/use=
r/SendEmail.jtp?type=3Dnode&node=3D21035&i=3D0" target=3D"_top" rel=
=3D"nofollow" link=3D"external">[hidden email]</a>> writes:
<o:p></o:p></span></p>
<div>
<p class=3D"MsoNormal"><span lang=3D"EN-US"><br>
> Bj=C3=B8rn Mork wrote: <br>
>> Perfectly understandable. I'm not going to claim that there are ma=
ny <br>
>> Linux users who care about 3G & LTE, so I'm not surprised that=
no big <br>
>> customers require it. Just judging by looking at my co-workers, wh=
o <br>
>> mostly use Thinkpads with 3G modules and have free mobile broadban=
d, I <br>
>> do not see many real users. But there are some, including some Lin=
ux <br>
>> users. <br>
> <br>
> One thing to bear in mind is that Android tablets & phones support=
3G & <br>
> LTE and Android is built on Linux, so the drivers are out there, somew=
here. <o:p>
</o:p></span></p>
</div>
<p class=3D"MsoNormal" style=3D"margin-bottom:12.0pt"><span lang=3D"EN-US">=
<br>
Well, although both chips and the kernel is mostly the same, the <br>
interfaces between them are actually quite different. Laptop modems <=
br>
interface to the host via USB (even if the physical slot is m.2 or <br>
mini-PCIe), while the Android devices usually have a shared memory <br>
interface between modem and host. This makes the drivers pretty <br>
different. So you can't just take an Android driver and use it on a <=
br>
laptop, even if the LTE chip is e.g. a Qualcomm MDM9200 or Intel XMM7160 <b=
r>
in both systems. <br>
<br>
But mobile broadband USB modems designed for Windows8 systems have to <br>
support the CDC MBIM class. And we do have a class driver for that in=
<br>
Linux. So in theory, the modems should all just work out of the box. =
<br>
<br>
In practice we may have to change a few minor things though. For <br>
example, to support the MDM9200 based Sierra Wireless MC7710 we had to <br>
allow a CDC MBIM function with no CDC Union descriptor (required by the <br=
>
spec, but obviously not by Microsoft and therefore "forgotten" by=
<br>
Sierra). And we also had to make the driver terminate all transfers <=
br>
with a short packet, even though the spec allows dropping the Zero <br>
Length Packet on maximum length transfers. <br>
<br>
<br>
<br>
Bj=C3=B8rn <br>
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=09<div class=3D"signature" style=3D"margin-top:1em;color:#666666;font-size=
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=09=09=09=09If you meet any Linux compatibility issues on ThinkPads, please=
try to ping me, I will check if there is anything I can help.
=09=09=09</div>
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