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

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Message-ID: <90cba8fa-e6a9-4dab-a4ea-fa96d570a870@gmx.de>
Date: Sun, 27 Apr 2025 00:52:33 +0200
From: Armin Wolf <W_Armin@....de>
To: "Rafael J. Wysocki" <rafael@...nel.org>
Cc: rui.zhang@...el.com, 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 26.04.25 um 15:12 schrieb Rafael J. Wysocki:

> On Sat, Apr 26, 2025 at 1:20 AM Armin Wolf <W_Armin@....de> wrote:
>> 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.
> Sure.
>
> I'm going to get to them next week, probably on Monday.

Ok, thanks.

Armin Wolf