linux-kernel - Re: [PATCH 0/3] ACPI: thermal: Properly support the

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Message-ID: <91ea8aed-5f98-4e4e-b3ee-fdc86d54f787@gmx.de>
Date: Sat, 26 Apr 2025 01:20:47 +0200
From: Armin Wolf <W_Armin@....de>
To: rafael@...nel.org, rui.zhang@...el.com
Cc: lenb@...nel.org, linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/3] ACPI: thermal: Properly support the _SCP control
 method

Am 10.04.25 um 18:54 schrieb Armin Wolf:

> The ACPI specification defines an interface for the operating system
> to change the preferred cooling mode of a given ACPI thermal zone.
> This interface takes the form of a special ACPI control method called
> _SCP (see section 11.4.13 for details) and is already supported by the
> ACPI thermal driver.
>
> However this support as many issues:
>
>   - the kernel advertises support for the "3.0 _SCP Extensions" yet the
>     ACPI thermal driver does not support those extensions. This may
>     confuse the ACPI firmware.
>
>   - the execution of the _SCP control method happens after the driver
>     retrieved the trip point values. This conflicts with the ACPI
>     specification:
>
> 	"OSPM will automatically evaluate _ACx and _PSV objects after
> 	 executing _SCP."
>
>   - the cooling mode is hardcoded to active cooling and cannot be
>     changed by the user.
>
> Those issues are fixed in this patch series. In the end the user
> will be able to tell the ACPI firmware wether he prefers active or
> passive cooling. This setting will also be interesting for
> applications like TLP (https://linrunner.de/tlp/index.html).
>
> The whole series was tested on various devices supporting the _SCP
> control method and on a device without the _SCP control method and
> appears to work flawlessly.

Any updates on this? I can proof that the new interface for setting the cooling mode
works. Additionally the first two patches fix two issues inside the underlying code
itself, so having them inside the mainline tree would be beneficial to users.

Thanks,
Armin Wolf

>
> Armin Wolf (3):
>    ACPI: OSI: Stop advertising support for "3.0 _SCP Extensions"
>    ACPI: thermal: Execute _SCP before reading trip points
>    ACPI: thermal: Allow userspace applications to change the cooling mode
>
>   .../ABI/testing/sysfs-driver-thermal          |  14 ++
>   MAINTAINERS                                   |   1 +
>   drivers/acpi/osi.c                            |   1 -
>   drivers/acpi/thermal.c                        | 129 ++++++++++++++++--
>   4 files changed, 133 insertions(+), 12 deletions(-)
>   create mode 100644 Documentation/ABI/testing/sysfs-driver-thermal
>
> --
> 2.39.5
>
>