linux-kernel - Re: [PATCH v2 0/6] ACPI fan

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <ec099f39-89a2-46ee-a10c-1350ecf7fc83@gmx.de>
Date: Wed, 22 Oct 2025 23:41:44 +0200
From: Armin Wolf <W_Armin@....de>
To: rafael@...nel.org, lenb@...nel.org
Cc: linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/6] ACPI fan _DSM support

Am 08.10.25 um 01:41 schrieb Armin Wolf:

> Microsoft has designed a _DSM interface for the ACPI fan device [1]
> that allows the OS to set fan speed trip points. The ACPI firmware
> will notify the ACPI fan device when said trip points are triggered.
>
> Unfortunately some device manufacturers (like HP) blindly assume that
> the OS will use this _DSM interface and thus only update the fan speed
> value returned by the _FST control method when sending a notification
> to the ACPI fan device. This results in stale fan speed values being
> reported by the ACPI fan driver [2].
>
> The first patch performs a simple cleanup in order to reduce the usage
> of the acpi_device struct. The second patch fixes an issue with some
> 64-bit ACPI implementations where an invalid value was reported
> instead of the standard ACPI placeholder value (0xFFFFFFFF). The third
> patch fixes an unrelated issue inside the hwmon support code while the
> next two patches add support for the ACPI fan notifications as
> specified in ACPI 11.2.3. The last patch finally adds support for the
> Microsoft _DSM interface.
>
> All patches where tested with a custom SSDT [3] and the acpi_call [4]
> kernel module and appear to work just fine.

Any thought on this? I tested it with a custom SSDT, so i can prove that
those patches work.

Thanks,
Armin Wolf

> [1] https://learn.microsoft.com/en-us/windows-hardware/design/device-experiences/design-guide
> [2] https://github.com/lm-sensors/lm-sensors/issues/506
> [3] https://github.com/Wer-Wolf/acpi-fan-ssdt/blob/master/ssdt-dsm.asl
> [4] https://github.com/nix-community/acpi_call
>
> Changes since v1:
> - use acpi_evaluate_dsm_typed() during _DSM initialization
> - send ACPI netlink event when after handling a ACPI notification
>
> Armin Wolf (6):
>    ACPI: fan: Use ACPI handle when retrieving _FST
>    ACPI: fan: Workaround for 64-bit firmware bug
>    ACPI: fan: Use platform device for devres-related actions
>    ACPI: fan: Add basic notification support
>    ACPI: fan: Add hwmon notification support
>    ACPI: fan: Add support for Microsoft fan extensions
>
>   drivers/acpi/fan.h       |  47 +++++++-
>   drivers/acpi/fan_attr.c  |   2 +-
>   drivers/acpi/fan_core.c  | 254 ++++++++++++++++++++++++++++++++++++---
>   drivers/acpi/fan_hwmon.c |  32 ++---
>   4 files changed, 302 insertions(+), 33 deletions(-)
>