Re: [BUG] ideapad_laptop: fans do not ramp up properly under CPU load on Lenovo IdeaPad 3 15ALC6 Ub (82KU)

[Sourajyoti Basak]

On 06/07/26 10:20 pm, Sourajyoti Basak wrote:
> On 02/06/26 8:43 pm, Sourajyoti Basak wrote:
>> On 09/05/26 9:00 pm, Sourajyoti Basak wrote:
>>> Hello,
>>>
>>> I am using a Lenovo IdeaPad 3 15ALC6 Ub (82KU), and I am encountering an
>>> issue where the laptop fans do not respond appropriately to increasing
>>> CPU temperatures under Linux.
>>>
>>> System information:
>>> Laptop: Lenovo IdeaPad 3 15ALC6 Ub
>>> BIOS version:GLCN46WW
>>> System performance mode in BIOS: Extreme Performance
>>> Kernel: Linux 7.0.5-1-cachyos
>>> Distribution: CachyOS
>>> CPU: AMD Ryzen 5 5500U (12) @ 4.06 GHz
>>>
>>> Issue description:
>>> Under sustained CPU load (for example using stress -c $(nproc)), CPU
>>> temperatures rapidly increase to around 95-100°C. However, the fans do
>>> not ramp to maximum speed as expected. Therefore, the system begins
>>> thermal throttling after some time in this state.
>>>
>>> As a result:
>>>
>>> - The CPU reaches thermal throttling temperatures.
>>> - CPU frequencies drop significantly once throttling begins.
>>> - Fan RPM appears capped or insufficient despite high temperatures.
>>> - The issue appears consistently reproducible on my laptop and another
>>>   person's laptop.
>>>
>>> Additional observations:
>>>
>>> - The issue persists across multiple recent kernel versions.
>>> - No hardware issues appear to be present. (Verified that the fans can
>>> indeed
>>>   ramp up to max speed by 
>>> `echo 1 | sudo tee /sys/bus/platform/drivers/ideapad_acpi/VPC2004:00/
>>> fan_mode`,
>>> which makes the fan enter "dust cleaning mode," causing it to ramp up to
>>> max speed
>>> and then back down to 0 RPM about 10 times.)
>>>
>>> Attachments:
>>> - DSDT in `DSDT.gz`
>>> - `dmidecode` in `dmidecode.txt`
>>>
>>> Data Collected during `stress -c $(nproc)` until thermal throttling:
>>> - EC information collected in a CSV file named `ec.csv`
>>>   (using `sudo ec_probe monitor -i 0.5 -r ec.csv` from the NBFC project)
>>> - `sensors` information in `sensors.log`
>>> - CPU frequencies in `cpu-freq.log`
>>> - `dmesg` in `dmesg-live.log`
>>>
>>> Thank you for your time.
>>>
>>> Best regards,
>>> Sourajyoti Basak
>>
>>
>> Hello everyone,
>>
>> Just a gentle ping on this bug report. The thermal throttling issue is
>> still present. Please let me know if there is any further ACPI/EC
>> debugging information I can provide.
>>
>> Best Regards,
>> Sourajyoti Basak
> 
> Hello everyone,
> 
> Just wanted to confirm that this issue still exists after updating to
> the latest BIOS version (`GLCN68WW`) and on the latest linux kernel
> version `Linux 7.1.2-3-cachyos`.
> 
> Best Regards,
> Sourajyoti Basak

Hello everyone,


This issue is still present even on the latest BIOS version (GLCN68WW)
and on the latest kernel version `Linux ideapad 7.1.4-1-cachyos`

Best Regards,
Sourajyoti Basak