Re: [REGRESSION] bitland-mifs-wmi: power-saver write is accepted but profile remains balanced on Redmi Book Pro 14 2022

On 7/21/26 6:20 PM, Thorsten Leemhuis wrote:
> [top posting, to facilitate processing]
>
> Hmm, nothing happened here.
>
> Mingyou Chen, this seems to be cause by a change of yours. Not totally
> sure yet if this qualifies as regression (sounds like one), but could
> you maybe share your view on all of this?
>
> Side note: Robert, have you tried if latest 7.2-rc works any better?
>
> Ciao, Thorsten
>
> On 7/13/26 20:35, Robert Munro wrote:
>> To: Mingyou Chen <[email protected]>, Hans de Goede
>> <[email protected]>, Ilpo Järvinen <[email protected]>
>> Cc: [email protected], [email protected]
>> Subject: [REGRESSION] bitland-mifs-wmi: power-saver write is accepted
>> but profile remains balanced on Redmi Book Pro 14 2022
>>
>> Hello,
>>
>> Linux 7.1's new bitland-mifs-wmi driver binds on my TIMI Redmi Book Pro
>> 14 2022 (TM2107) and exposes platform profiles, but selecting power-
>> saver is silently ineffective. The userspace request returns success
>> while the sysfs profile never leaves "balanced".
>>
>> This reproduces without KDE:
>>
>>      $ cat /sys/class/platform-profile/platform-profile-0/name
>>      bitland-mifs-wmi
>>
>>      $ cat /sys/firmware/acpi/platform_profile_choices
>>      low-power balanced balanced-performance performance
>>
>>      $ cat /sys/firmware/acpi/platform_profile
>>      balanced
>>
>>      $ powerprofilesctl set power-saver
>>      $ echo $?
>>      0
>>
>>      $ powerprofilesctl get
>>      balanced
>>
>>      $ cat /sys/firmware/acpi/platform_profile
>>      balanced
>>
>>      $ cat /sys/devices/system/cpu/cpufreq/policy0/
>> energy_performance_preference
>>      balance_performance
>>
>> I repeated the request while polling platform_profile every 50 ms. The
>> only observed value was "balanced"; no transient "low-power" state
>> appeared. The request completed in 162 ms with exit status 0. power-
>> profiles-daemon also persisted Profile=balanced afterward. There were no
>> relevant kernel or daemon log messages.
>>
>> Expected result:
>>
>> The advertised low-power profile is selected, platform_profile reads
>> "low-power", and the AMD P-State EPP becomes power-oriented.
>>
>> Actual result:
>>
>> The operation reports success, but firmware, power-profiles-daemon, and
>> all AMD CPU policies remain balanced.
>>
>> System information:
>>
>>      Distribution: CachyOS
>>      Kernel: 7.1.3-2-cachyos
>>      DMI vendor/product/board: TIMI / Redmi Book Pro 14 2022 / TM2107
>>      BIOS: TIMI RMARB4B0P1010, 2023-06-28
>>      CPU: AMD Ryzen 5 6600H with Radeon Graphics
>>      bitland_mifs_wmi srcversion: 0C0A58A1AE25437010C0B5E
>>      power-profiles-daemon: 0.30-3
>>      Power source during reproduction: AC online
>>      Active profile holds: none
>>      Other power managers (TLP, TuneD, auto-cpufreq): none
>>
>> powerprofilesctl identifies both drivers:
>>
>>      power-saver:
>>        CpuDriver: amd_pstate
>>        PlatformDriver: platform_profile
>>
>> The kernel taint value is 512 because of an unrelated AMDGPU display
>> warning during boot (dcn31_program_compbuf_size); bitland_mifs_wmi
>> itself is not tainted and emitted no warning during reproduction.
>>
>> This began after the 2026-06-24 update from Linux 7.0.12 to 7.1.1, which
>> introduced bitland-mifs-wmi (dc1ec4fa86b2). Power Saver worked before
>> that update. My installed 6.18 LTS kernel does not contain this driver,
>> but I have not yet performed an LTS or vanilla-mainline A/B test, so I
>> am explicitly reporting this as reproduced on a CachyOS kernel.
>>
>>
>> Regards,
>> Robert
>>
>> Assisted-by: OpenAI Codex:GPT-5
>>
>> Robert Munro
>> Director, Executive Team
>> [email protected] <mailto:[email protected]>
>> ethicsbowl.ca <https://ethicsbowl.ca>
>> Ethics Bowl Canada

Let me explain this,

The bitland-mifs-wmi driver was introduced on Linux 7.1

Previously, there wasn't a driver available for Bitland devices (Redmi 
hardware is OEM'd by Bitland), and |platform_profile| was non-functional.

This driver works well on my Bitland laptop (Lecoo Bellator N176).

The driver support for these generic OEM designs is pretty messy. We 
might need to introduce quirks into the driver because, despite sharing 
the same data structure, many implementation details differ across models.


And by the way, don't top post on kernel mailing lists.

--

Mingyou Chen