I can independently reproduce this issue on a Lenovo ThinkPad X13 Yoga Gen 1 (20SY) with the Fibocom L860-GL / Intel XMM7560 modem.
The problem occurs on Debian 12 (kernel 6.1) and Ubuntu 26.04 (kernels 7.0.0-14, 7.0.0-31 and 7.0.0-42). I have also confirmed that LTE mobile data works correctly under Windows 11 with Wi-Fi disabled, using the same laptop, modem and SIM. # [iosm][XMM7560] Fibocom L860-GL: `ch[6]: confused phase 3` and MBIM initialization timeout on ThinkPad X13 Yoga Gen 1 ## Summary The integrated Fibocom L860-GL (Intel XMM7560) LTE modem on a Lenovo ThinkPad X13 Yoga Gen 1 fails to initialize under Linux. The `iosm` driver binds to the PCIe device and creates the WWAN AT and MBIM ports. However, the kernel reports `ch[6]: confused phase 3`, and ModemManager subsequently times out and declares the modem unusable. **The same hardware successfully connects to the internet over LTE under Windows 11 with Wi-Fi disabled.** Windows also detects the SIM and reports modem firmware `18600.5001.00.35.01.57`. ## Hardware - Laptop: Lenovo ThinkPad X13 Yoga Gen 1 - Machine type/model: `20SYS4BY00` - Machine type: `20SY` - Processor: Intel Core i5-10310U - Modem: Fibocom L860-GL / Intel XMM7560 - PCI ID: `8086:7560` - PCI subsystem ID: `1cf8:8601` - PCI address: `0000:06:00.0` - Linux kernel driver: `iosm` - Modem firmware: `18600.5001.00.35.01.57` ## Affected Linux kernels The failure has been reproduced with: - Debian 12 Live: `6.1.0-50-amd64` - Ubuntu 26.04: `7.0.0-14-generic` - Ubuntu 26.04: `7.0.0-31-generic` - Ubuntu 26.04: `7.0.0-42-generic` ## Kernel diagnostics The kernel detects the device and attaches the expected WWAN ports: ```text pci 0000:06:00.0: [8086:7560] type 00 class 0x0d4000 PCIe Endpoint iosm 0000:06:00.0: enabling device (0000 -> 0002) wwan wwan0: port wwan0at0 attached wwan wwan0: port wwan0at1 attached wwan wwan0: port wwan0mbim0 attached iosm 0000:06:00.0: ch[6]: confused phase 3 ``` ## ModemManager diagnostics ModemManager detects the device and creates a modem object using its Intel plugin: ```text creating modem with plugin 'Intel' and '4' ports (1cf8:8086:7560) modem for device ... successfully created ``` Initialization then fails: ```text [modem0] couldn't start initialization: Transaction timed out fatal error initializing: Fatal error: modem is unusable ``` The modem is not available through `mmcli -L`. A direct MBIM capabilities query using `mbimcli` also failed with an input/output error. ## Windows 11 comparison The same laptop and integrated modem were tested using Windows 11 booted from external storage. Windows identified the device as Fibocom L860-GL and reported firmware version `18600.5001.00.35.01.57`. After restarting Windows, the SIM was detected. **With Wi-Fi disabled, the laptop successfully loaded a website using its cellular LTE connection.** This confirms that the modem, SIM reader and LTE data path are functional under Windows. ## Troubleshooting performed - Tested four Linux kernel builds spanning versions 6.1 and 7.0. - Confirmed PCI enumeration and binding to the `iosm` driver. - Confirmed creation of AT and MBIM ports. - Confirmed the recurring `ch[6]: confused phase 3` kernel error. - Confirmed ModemManager initialization timeouts. - Tested direct MBIM communication, which failed. - Installed Lenovo's L860-GL-16 FCC-unlock package and verified the `8086:7560` handler. - Tested after complete shutdown and cold boot. - Successfully tested LTE connectivity under Windows 11 with Wi-Fi disabled. The Linux initialization failure persists. ## Expected behavior The `iosm` driver should establish working communication with the XMM7560 modem, allowing ModemManager to initialize the device and establish an LTE connection. ## Actual behavior The kernel reports `ch[6]: confused phase 3`. MBIM communication fails, and ModemManager times out during initialization. ## Related reports - Linux kernel bug #217200: https://bugzilla.kernel.org/show_bug.cgi?id=217200 - Ubuntu bug #2171011: https://bugs.launchpad.net/bugs/2171011 The kernel bug documents a potentially related historical regression. It is not yet established that the present failure has the same root cause. ## Questions 1. What conditions cause the `iosm` driver to report `ch[6]: confused phase 3`? 2. Could this indicate a channel-state synchronization problem between `iosm` and the XMM7560 firmware? 3. Is firmware `18600.5001.00.35.01.57` known to work with the upstream `iosm` driver? 4. Are any relevant fixes or diagnostic patches available? 5. Which additional traces would be most useful for investigating the MBIM initialization timeout? ** Bug watch added: Linux Kernel Bug Tracker #217200 https://bugzilla.kernel.org/show_bug.cgi?id=217200 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2171011 Title: Fibocom L860-GL (Intel XMM7560): iosm "confused phase 3", modem initialization times out To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2171011/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
