[Bug 221353] New: ideapad_acpi: fan_mode values 1/2/4 all trigger dust cleaning mode

[Bug 221353] New: ideapad_acpi: fan_mode values 1/2/4 all trigger dust cleaning mode

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=221353

            Bug ID: 221353
           Summary: ideapad_acpi: fan_mode values 1/2/4 all trigger dust
                    cleaning mode
           Product: Drivers
           Version: 2.5
          Hardware: Intel
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P3
         Component: Platform_x86
          Assignee: drivers_platform_x86@kernel-bugs.osdl.org
          Reporter: basak.sb2006@gmail.com
        Regression: No

# Hardware

## DMI

- system-manufacturer: `LENOVO`
- system-version: `IdeaPad 3 15ALC6 Ub`
- system-product-name: `82KU`
- bios-version: `GLCN46WW`

## Kernel

- `uname -a`: `Linux ideapad 6.19.11-arch1-1 #1 SMP PREEMPT_DYNAMIC Thu, 02 Apr
2026 23:33:01 +0000 x86_64 GNU/Linux`


# Description

According to
[Documentation/ABI/testing/sysfs-platform-ideapad-laptop](https://github.com/torvalds/linux/blob/f5459048c38a00fc583658d6dcd0f894aff6df8f/Documentation/ABI/testing/sysfs-platform-ideapad-laptop),

fan_mode supports:
0 = Super Silent
1 = Standard
2 = Dust Cleaning
4 = Efficient Thermal Dissipation

However, on this device:
- Writing 1, 2, or 4 all produce identical behavior.
- Fan enters a pulsing high-speed mode where it ramps up to max speed and then
ramps down to 0 RPM about 10 times. Consistent with "dust cleaning" mode.
- Only value 0 behaves differently. It changes it to the default/"Super Silent"
mode.

Here is the observation table:
| Input | Transition (read immediately afterwards)              | Finish (read
after 1 min or so)|
|-------|-------------------------------------------------------|--------------------------------|
| 0     | immediately 133, minimal fan activity                 | 133          
                 |
| 1     | 3, enters "dust cleaning" mode                        | 5            
                 |
| 2     | 3                                                     | 5            
                 |
| 4     | 3                                                     | 5            
                 |


# Steps to Reproduce

1. Switch to a fan mode.
- echo 0 | sudo tee  /sys/bus/platform/drivers/ideapad_acpi/VPC2004:00/fan_mode
- echo 1 | sudo tee  /sys/bus/platform/drivers/ideapad_acpi/VPC2004:00/fan_mode
- echo 2 | sudo tee  /sys/bus/platform/drivers/ideapad_acpi/VPC2004:00/fan_mode
- echo 4 | sudo tee  /sys/bus/platform/drivers/ideapad_acpi/VPC2004:00/fan_mode

2. Observe that all of them except mode "0" (a.k.a. "Super Silent" mode) make
the fan enter the "dust cleaning" mode.


# Expected

Different fan behaviors per documented modes.


# Actual

All non-zero modes behave like dust cleaning.


Best Regards,
Sourajyoti Basak

-- 
You may reply to this email to add a comment.

You are receiving this mail because:
You are watching the assignee of the bug.