https://bugzilla.kernel.org/show_bug.cgi?id=221155
Bug ID: 221155
Summary: Fan control not working on ThinkPad L480 (20LS002DPG)
Product: ACPI
Version: 2.5
Hardware: Intel
OS: Linux
Status: NEW
Severity: normal
Priority: P3
Component: Power-Fan
Assignee: [email protected]
Reporter: [email protected]
Regression: No
The fan control interface is accessible but fans do not spin at full speed even
when set to maximum level or full-speed mode. The fans work correctly under
Windows.
System Information:
- ThinkPad Model: Lenovo Thinkpad L480 (20LS002DPG)
- BIOS Version: R0QET69W (1.46)
- Kernel Version: 6.16.1-arch1-1
- OS: Arch Linux
Reproduction Steps:
1. Set fan level to maximum:
sudo sh -c 'echo "level 7" > /proc/acpi/ibm/fan'
2. Verify fan level:
cat /proc/acpi/ibm/fan
3. Check fan speed:
cat /sys/class/hwmon/hwmon4/fan1_input /sys/class/hwmon/hwmon4/fan2_input
Output: 0 0 (0 RPM)
Expected Behavior:
Fans should spin at full speed when set to level 7 or full-speed mode.
Actual Behavior:
Fan readings always show 0 RPM regardless of level setting. PWM interface shows
100% duty cycle but fans don't spin.
Additional Information:
- thinkpad_acpi.fan_control=1 and thinkpad_acpi.ec_fan_control=1 kernel
parameters have been tested
- ThinkPad ACPI driver detects fan control: "ECFW with fan RPM as decimal in EC
register" and "secondary fan control detected & enabled"
Relevant dmesg Output:
[ 1.845062] thinkpad_acpi: ECFW with fan RPM as decimal in EC register
[ 1.853666] thinkpad_acpi: secondary fan control detected & enabled
Kernel Command Line:
BOOT_IMAGE=/vmlinuz-linux root=UUID=44560a26-03b7-4d22-a0c0-4b2dca1a2c5d rw
thinkpad_acpi.fan_control=1 thinkpad_acpi.ec_fan_control=1 loglevel=3 quiet
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