Lenovo ThinkPad X1 Carbon (Gen 6)

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Tip: A great resource for thinkpads is https://www.thinkwiki.org/wiki/ThinkWiki

Model description

The Lenovo ThinkPad X1 Carbon, 6th generation is an ultrabook introduced in early 2018. It comes in several variants(20KH* and 20KG*) and features a 14" screen, 8th-gen Intel Core processors and integrated Intel UHD 620 graphics.

To ensure you have this version, install the package dmidecode and run:

# dmidecode -t system | grep Version

Version: ThinkPad X1 Carbon 6th

Support

Device Working
Intel graphics Yes
Wireless network Yes
Native Ethernet with included dongle Yes
Mobile broadband Untested
ALSA Yes
Touchpad Yes*
TrackPoint Yes
Camera Yes
Fingerprint Reader No
Power management Yes
Bluetooth Untested
microSD card reader Untested

* via workaround

Suspend issues

Suspend-to-RAM (S3) not supported by default

The 6th Generation X1 Carbon supports S0i3 (also known as Windows Modern Standby) and does not support the S3 sleep state. A guide exists with instructions for patching ACPI DSDT tables to add S3 support.

A forum thread has further discussion related to this issue.

S0i3 sleep support

From the Lenovo forums: Add the following kernel parameter to enable s0i3 sleep support:

acpi.ec_no_wakeup=1
Note: This disables wakeup/resume via lid open.

You might also need to disable the Realtek memory card reader (which appears to use a constant 2-3 W) either via the BIOS or via

echo "2-3" | sudo tee /sys/bus/usb/drivers/usb/unbind

BIOS configurations

  • Config -> Thunderbolt BIOS Assist Mode - Set to "Enabled". When disabled, on Linux, power usage appears to be significantly higher because of a substantial number of CPU wakeups during s2idle.

Power management/Throttling issues

Due to wrong configured power management registers the CPU may consume a lot less power than under windows and the thermal throttling occurs at 80°C (97°C when using Windows, see T480s throttling bug).

There is a post in the official Lenovo forum to inform Lenovo about this issue.

Temporary fix

Until Lenovo fixes this issue, you can manually set the limit.

To begin, install msr-tools

Create the file /usr/local/bin/cpu-throttling.sh (making it executable) containing the following:

#!/bin/bash

/bin/modprobe msr
wrmsr -a 0x1a2 0x3000000 # which sets the offset to 3 C, so the new trip point is 97 C 

Then create the associated service file /etc/systemd/system/cpu-throttling.service:

[Unit]
Description=set cpu heating limit to 97°c

[Service]
ExecStart=/usr/local/bin/cpu-throttling.sh
RemainAfterExit=no

[Install]
WantedBy=timers.target

And also the timer in /etc/systemd/system/cpu-throttling.timer:

[Unit]
Description=set cpu heating limit to 97°c every minute

[Timer]
OnActiveSec=60
OnUnitActiveSec=60
Unit=cpu-throttling.service

[Install]
WantedBy=timers.target

Then, enable it:

# systemctl enable cpu-throttling.timer

Reboot and check with:

# rdmsr -f 29:24 -d 0x1a2

3

TrackPoint and Touchpad issues

On the 20KG model, the Touchpad(Synaptics) and TrackPoint(Elantech) do not work together, one has to disable the TrackPoint in BIOS to get the Touchpad to work reliably. The root of the issue seems to be that the default loading of the TrackPoint via ancient PS/2 drivers conflicts with Touchpad loading. Synaptics has introduced a new way of doing things named RMI(4) that fixes some those issues. Further explanation is collected in this thread.

There are several workarounds available:

Load i2c_i801 kernel module on boot

Open /etc/modules-load.d/touchpad.conf and add:

 i2c_i801
 elan_i2c
 rmi_smbus

This enables loading the input devices over rmi4 with recent kernels.

Then add synaptics_intertouch=1 to the psmouse kernel options, for example in the cmdline of the boot loader:

 [...] root=/dev/sda1 rw psmouse.synaptics_intertouch=1 [...]

Compile kernel with CONFIG_RMI4 options enabled

Someone has reported success with enabling RMI4 config flags for kernel compilation.

Wait for patches to be included in kernel

Benjamin Tissoires from Red Hat has proposed patches that enable Elantech TrackPoints to be loaded over rmi and whitelist X1C6 ids.


References

Additional resources