Arch Linux

wade owen watts

Member

Registered: 2025-10-25

Posts: 1

ThinkPad X1 Yoga Gen 8 – Fibocom FM350 (MediaTek T700) WWAN modem not

Hi everyone,

I’m trying to get the Fibocom FM350 5G WWAN module (MediaTek T700) working on my Lenovo ThinkPad X1 Yoga Gen 8 running Arch Linux.
According to the [Arch Wiki](https://wiki.archlinux.org/title/Lenovo … 28Gen_8%29), this modem should work with kernel ≥ 6.6 and ModemManager ≥ 1.22 after running Lenovo’s FCC unlock tool once — but mine still won’t power on.

System information

6.17.5-arch1-1

linux 6.17.5.arch1-1
linux-headers 6.17.5.arch1-1
linux-firmware 20251010.xxx
modemmanager 1.24.x
libmbim 1.32.0

Secure Boot` is disabled.
rfkill list shows no blocks (both Soft and Hard blocked = no).

Current behaviour

The kernel detects the PCI device:

08:00.0 Wireless controller [0d40]: MEDIATEK Corp. T700 5G Modem [14c3:4d75] (rev 01)

But it never creates `/dev/cdc-wdm0`:

ls /dev | grep cdc-wdm
# → (no output)

Driver messages:

dmesg | grep -i t7xx
[   25.902204] mtk_t7xx 0000:08:00.0: enabling device (0000 -> 0002)
[ 2169.494545] mtk_t7xx 0000:08:00.0: Runtime PM usage count underflow!

ModemManager sees the device in a “low power / disabled” state and can’t enable it:

mmcli -m 0 -e
error: couldn't enable the modem: 'GDBus.Error:org.freedesktop.ModemManager1.Error.Core.Retry: Retry: Invalid transition'

journalctl -u ModemManager | grep -i fcc

shows nothing.

---

Steps already attempted

1. **Lenovo FCC Unlock tool** (`DPR_Fcc_unlock_service` from Lenovo package n3xwp04w)

   * Installed and executed with

     

     sudo env LD_LIBRARY_PATH=$(pwd) ./DPR_Fcc_unlock_service
     

   * The binary runs but reports

     

     ls: cannot access '/dev/wwan*': No such file or directory
     

     → so it can’t find the device nodes.

2. **Re-loading the MediaTek driver:**

   

   sudo modprobe -r mtk_t7xx
   sudo modprobe mtk_t7xx
   

   No change — still no `/dev/cdc-wdm0`.

3. **FCC unlock attempts via libmbim 1.32:**

   

   sudo mbimcli -d /dev/cdc-wdm0 --fcc-auth
   # or --device-fcc-auth
   

   → both fail because `/dev/cdc-wdm0` doesn’t exist.

4. **acpi_call tests**
   Tried enabling WWAN via ACPI calls (`\_SB.PCI0.LPCB.EC.HKEY.WWAN`, `WWAN_ON`, etc.)
   None changed anything; `/dev/cdc-wdm0` never appears.

5. **BIOS / EC checks**

   * WWAN = Enabled in BIOS
   * rfkill = unblocked
   * Kernel and firmware fully up to date

6. **DSDT analysis**

   * Only references to `V3P3A_WWAN` and `CONNECTIVITY_WWAN` found, no `_ON`/`_OFF` method → power controlled by EC firmware, not ACPI.

---

Current status:
Everything (kernel, firmware, ModemManager, libmbim) is up-to-date, but the modem remains completely off — no MBIM or AT ports appear, so ModemManager can’t talk to it.
`mtk_t7xx` loads and unloads cleanly but immediately powers down the device.
The same Lenovo FCC unlock binary works under Ubuntu 22.04 LTS and Fedora 39 (verified by other users / Lenovo docs).

---

Questions:
1. Has anyone managed to get the **FM350 / MediaTek T700** WWAN modem powered on under pure Arch (kernel 6.17)?
2. Is there a kernel patch or module parameter to trigger the EC/FCC unlock automatically?
3. Does Arch’s packaged `mtk_t7xx` driver lack Lenovo’s FCC-unlock hook that Fedora / Ubuntu include?
4. Any reliable way to run Lenovo’s `DPR_Fcc_unlock_service` successfully on Arch Linux?

Any pointers would be very much appreciated.
Thanks in advance!

---

System summary:
* Lenovo ThinkPad X1 Yoga Gen 8 (Type 21HQ)
* BIOS v1.32
* WWAN module: Fibocom FM350 (MediaTek T700, PCI ID 14c3:4d75)
* Arch Linux x86_64 (fully updated, kernel 6.17.5)
* ModemManager 1.24.x, libmbim 1.32.0
* Secure Boot off, WWAN enabled in BIOS, rfkill unblocked

---

Would anyone be able to confirm if the EC unlock mechanism for this modem is already merged in mainline or if Lenovo’s proprietary FCC unlock tool is still required under Arch?

---

Last edited by wade owen watts (2025-10-27 18:31:23)