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intelfx
SCSI Port
Posts: 47
Registered: ‎09-15-2016
Location: RU
Views: 997
Message 91 of 120

Re: Linux status of Fibocom L850-Gl


@MarkRHPearson wrote:

First off my apologies - I thought the driver team was looking into this, but I didn't have all the details. I should have checked harder before my initial post. Still new to the team and still learning...

 

I got the following back from our driver team:
"Intel is not supporting PCIe configuration and they have no plan to do so.

Also, to support WWAN feature legally, we need to provide DPR(Dynamic Power Reduction) software. FCC regulates the energy that is absorbed by human body to a certain limit. This is called SAR requirement. To meet this regulation, we need to constantly check the orientation and proximity of the system and dynamically reduce radio output power if the location of the antenna(s) get too close to human body. To write DPR we need API to control RF output. Intel does not provide such API neither."

 

I think that explains the reasons why it's not available now - and why it's not obvious to enable it.

 

I'd be interested to get some feedback from folk who understand this better for opinions/corrections. Are there any open source tools/projects out there that can be used to move this item forward?


Great — now we can talk.

 

First. What do you mean by specifically "Intel is not supporting PCIe configuration"? There are Windows drivers for it, so surely it should have been supported at least at some point ago? Or do you mean that they aren't supporting PCIe anymore, and that's why it's infeasible to develop a new driver for this configuration? Then I would like to ask you again to please comment on the issue of USB interface (see my earlier reply above).

 

Second. Regarding DPR (SAR back-off), how is it implemented in the Windows driver? Unfortunately there is nothing in the open-source driver stack to control SAR back-off (and even if there was, you cannot legally guarantee it will be used every time). Does this legally stop Lenovo from as much as hinting that WWAN could be used in Linux?

dbao
Punch Card
Posts: 101
Registered: ‎11-07-2009
Location: US
Views: 974
Message 92 of 120

Re: Linux status of Fibocom L850-Gl


@intelfx wrote:

@MarkRHPearson

 

First. What do you mean by specifically "Intel is not supporting PCIe configuration"? There are Windows drivers for it, so surely it should have been supported at least at some point ago? Or do you mean that they aren't supporting PCIe anymore, and that's why it's infeasible to develop a new driver for this configuration? Then I would like to ask you again to please comment on the issue of USB interface (see my earlier reply above).

 


Fibocom windows driver is not a generic PCIe driver. It provides PCIe-USB immulator so regular Quacomm modem interface driver will work under windows.

 

The second question, leagally prohibit Lenovo sell Linux device with WWAN pre-installed in US, not else. But CFR does not prohibit end user install radio device, as long as the power does not exceed max limit per frequency (in this case, 1W without license). Many vendors sell laptops without whitelist in US, for example, Panasonic sells Toughbook with WWAN to US law enforcement. They do not enforce whitelist.

NikosAlexandris
SCSI Port
Posts: 77
Registered: ‎04-28-2014
Location: IT
Views: 941
Message 93 of 120

Re: Linux status of Fibocom L850-Gl


@MarkRHPearson wrote:

..

I got the following back from our driver team:
"Intel is not supporting PCIe configuration and they have no plan to do so.

Also, to support WWAN feature legally, we need to provide DPR(Dynamic Power Reduction) software. FCC regulates the energy that is absorbed by human body to a certain limit. This is called SAR requirement. To meet this regulation, we need to constantly check the orientation and proximity of the system and dynamically reduce radio output power if the location of the antenna(s) get too close to human body. To write DPR we need API to control RF output. Intel does not provide such API neither."


The question that natural comes after this is: how does the Windows DPR driver work? Is there access to a relevant API?

A few links:

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NikosAlexandris
SCSI Port
Posts: 77
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Location: IT
Views: 876
Message 94 of 120

Re: Linux status of Fibocom L850-Gl

Of interest: Linux drivers for XMM 7360 LTE #7.

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NikosAlexandris
SCSI Port
Posts: 77
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Location: IT
Views: 866
Message 95 of 120

Re: Linux status of Fibocom L850-Gl


@rushforth wrote:

 ..

Trying to understand which issue it is, and why other laptops with tihs card work in Linux and seeminly are legal.


 

Here instructions to remove and install the WWAN module in Dell's Latitude 5501 model: Latitude 5501 Owners Manual (2). Yes, this laptop features the same Fibocom module! See also the Mobiles Breitband section in Latitude 5501 Owners Manual.

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NikosAlexandris
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Message 96 of 120

Re: Linux status of Fibocom L850-Gl


@MarkRHPearson wrote:

..

I got the following back from our driver team:
"Intel is not supporting PCIe configuration and they have no plan to do so.

..."


Here an "official" reply by Intel via twitter, which is more or less in line with the statement that Intel has no plans to support this module under linux: https://twitter.com/dannyalgaaf/status/981659914199330819?s=20.

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Lenovo Employee MarkRHPearson
Lenovo Employee
Posts: 58
Registered: ‎07-22-2019
Location: CA
Views: 680
Message 97 of 120

Re: Linux status of Fibocom L850-Gl

Hi all,

 

I discussed the Fibocom 850 WAN device with the Device Driver team and have a better understanding of the challenges with supporting it. Below are some notes from our discussion:

 

  • Intel are not providing Linux support for this part. 
  • There are strict FCC requirement for wireless devices such that the transmitting antenna must be treated as an integral part of the overall device. On this platform it means that there are a few levels of HW authentication that take place and some of this needs to be done in the software driver. This means that a Lenovo supported open source solution is likely not legally feasible at present.
  • The WWAN chipset can support both USB and PCIe but we enabled PCIe bus configuration to provide improved performance. USB interface is disabled. USB is not fast enough to transfer data to support full LTE speed.
  • The SAR/DPR requirement is also a problem (the ability to limit the output power depending on how close it is to you). If Lenovo provided any support for this device we would have to make sure it was fully certified.

Let me know if there are any questions. There are some Lenovo confidential pieces involved around the authentication and how/why that is done so some responses may be delayed while I check with the driver team what I can say but I'll do my best to give clarification where possible.

 

dbao
Punch Card
Posts: 101
Registered: ‎11-07-2009
Location: US
Views: 645
Message 98 of 120

Re: Linux status of Fibocom L850-Gl


@MarkRHPearson wrote:
  • USB interface is disabled. USB is not fast enough to transfer data to support full LTE speed.

Not true. L850GL only support up to Cat9 LTE. Your competitor, EM7565 is a Cat12 LTE card, which only has USB interface. 

 

USB can 100% support even full Gigabit speed. There is USB ethernet adapter for X1 made by Lenovo. The reason NOT to use USB is, wwan wake up time is much longer under USB so it cannot be able to used as "always on" network device. It has nothing to do with LTE speed.

 

Since x1y3 (and x1y4), Lenovo removed deep sleep state from BIOS and also remove USB interface for wwan in order to claim this laptop as an always-on machine. But, as I think, this is 100% failure. Still remember lenghty, notorious, painful BIOS deep sleep bug fix?

 

 

intelfx
SCSI Port
Posts: 47
Registered: ‎09-15-2016
Location: RU
Views: 620
Message 99 of 120

Re: Linux status of Fibocom L850-Gl


@MarkRHPearson wrote:

Hi all,

 

I discussed the Fibocom 850 WAN device with the Device Driver team and have a better understanding of the challenges with supporting it. Below are some notes from our discussion:

 

  • Intel are not providing Linux support for this part. 
  • There are strict FCC requirement for wireless devices such that the transmitting antenna must be treated as an integral part of the overall device. On this platform it means that there are a few levels of HW authentication that take place and some of this needs to be done in the software driver. This means that a Lenovo supported open source solution is likely not legally feasible at present.
  • The WWAN chipset can support both USB and PCIe but we enabled PCIe bus configuration to provide improved performance. USB interface is disabled. USB is not fast enough to transfer data to support full LTE speed.
  • The SAR/DPR requirement is also a problem (the ability to limit the output power depending on how close it is to you). If Lenovo provided any support for this device we would have to make sure it was fully certified.

Let me know if there are any questions. There are some Lenovo confidential pieces involved around the authentication and how/why that is done so some responses may be delayed while I check with the driver team what I can say but I'll do my best to give clarification where possible.

 


Thank you for your reply. Unfortunately, it raises more questions than it answers.

 


There are strict FCC requirement for wireless devices such that the transmitting antenna must be treated as an integral part of the overall device. On this platform it means that there are a few levels of HW authentication that take place and some of this needs to be done in the software driver. This means that a Lenovo supported open source solution is likely not legally feasible at present.

Does this mean that Lenovo is legally obliged to create obstacles for using this modem with open-source drivers under GNU/Linux? Or does this just mean that Lenovo can't endorse a specific open-source solution?

 


The WWAN chipset can support both USB and PCIe but we enabled PCIe bus configuration to provide improved performance. USB interface is disabled. USB is not fast enough to transfer data to support full LTE speed.

As far as I can see, having a functional USB interface that allegedly can't reach "full LTE speed" (even if that's true) is better than having no interface at all.

 

I have to stress this again — it is known that not just the chipset, but the modem itself supports both PCIe and USB configurations out of the box. It however implements a very primitive bus selection logic, where the modem locks itself into the PCIe configuration as soon as it "sees" the PCIe bus. Therefore the burden of "guiding" the modem into the correct configuration lies on the platform firmware, in this case on Lenovo.

 

With this in mind, what exactly are the obstacles for providing a firmware-level option (i. e. a toggle in BIOS Setup) to block PCIe on the WWAN M.2 slot, which will force the L850-GL modem into the USB configuration? Are they technical, legal or otherwise?

abrasive
Fanfold Paper
Posts: 6
Registered: ‎10-15-2019
Location: AU
Views: 318
Message 100 of 120

Re: Linux status of Fibocom L850-Gl

Oof, what a thread! I just got a T490 so time for me to jump in too.

I've done a bit of reverse engineering and come up with a couple of things.
One, a way to flip the modem to USB mode from within Linux.
And two, some of a PCI driver (enough to send AT commands, not enough to run MBIM).

You can find at least the former here:

https://github.com/abrasive/xmm7360

On my T490 the device ends up stuck in flight mode (AT+CFUN? returns 4,0 and MBIM power on requests return Busy).
I don't know if this is the WAN disable line to the M.2 slot and it's actually in flight mode? - but that doesn't appeared to be set up on this laptop (the GPIO used by the SWAN ACPI method isn't even set as an output).
I wonder if it actually depends on the ModemAuthenticator service that runs on Windows and "unlocks" the modem?
But then I'd expect it to boot in my Windows VM when I pass through the modem device, and it doesn't even with the ModemAuthenticator running. I haven't done any digging to see if the "Authenticator" is actually talking to it though.
I'm stumped so far and would be interested to hear how other people get on.

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