https://bugzilla.kernel.org/show_bug.cgi?id=214205
Bug ID: 214205
Summary: thermal sensor broken after resume, fan speed at 100%
speed on Lenovo ThinkPad Carbon X1 4th Gen
Product: ACPI
Version: 2.5
Kernel Version: 5.14.0-rc7.g61596f4
Hardware: Intel
OS: Linux
Tree: Mainline
Status: NEW
Severity: normal
Priority: P1
Component: EC
Assignee: [email protected]
Reporter: [email protected]
Regression: No
On Lenovo ThinkPad Carbon X1 4th Gen, fan speed often raises to max after
resume.
Reproducibility varies, but recently I get about 85% reproducibility.
The problem never appears on boot from poweroff.
But when it appears after resume, reboot does not help. Shutdown is required to
get fan back to work properly.
It can be worked around by repeated suspend/resume many times:
cat /proc/acpi/ibm/thermal | ( read t x y ; echo $x ; if test "$x" = -128 ;
then systemctl suspend ; fi )
With ~1% probability, a different problem appears: Fan does not stop during
resume. It may be related.
Another strange ACPI behavior, much less annoying: The computer often forgets
wakeup preferences for USB devices during the suspend/wake cycle, e. g.
/sys/bus/usb/devices/1-4.2.1.2/power/wakeup goes from enabled to disabled.
It is caused by the failed resume of the thermal sensor, which returns -128
instead of the correct value.
cat /proc/acpi/ibm/thermal
When it fails:
temperatures: -128 -128 0 0 0 0 0 0
When OK:
temperatures: 47 -128 0 0 0 0 0 0
sensors command shows the same problem.
Hardware:
ThinkPad X1 Carbon 4th
20FB002UMC
BIOS N1FET75W (1.49) 05/25/2021
Output of hwprobe:
https://linux-hardware.org/?probe=44d0412dd3
This bug is similar to bug 196129 for 5th Gen.
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