On Mon, Apr 28, 2025 at 2:31 PM Armin Wolf <W_Armin@xxxxxx> wrote: > > Am 27.04.25 um 00:52 schrieb Armin Wolf: > > > Am 26.04.25 um 15:12 schrieb Rafael J. Wysocki: > > > >> On Sat, Apr 26, 2025 at 1:20 AM Armin Wolf <W_Armin@xxxxxx> 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 > > > I am a bit ashamed of myself but i think we need to put this patch series on hold after all :(. > > The reason of this is that i am confused by the ACPI specification regarding _SCP: > > 11.1.2.1. OSPM Change of Cooling Policy > > When OSPM changes the platform’s cooling policy from one cooling mode to the other, the following occurs: > > 1. OSPM notifies the platform of the new cooling mode by running the Set Cooling Policy (_SCP) control method in all thermal zones and invoking the OS-specific Set Cooling Policy interface to all participating devices in each thermal zone. > > 2. Thresholds are updated in the hardware and OSPM is notified of the change. > > 3. OSPM re-evaluates the active and passive cooling temperature trip points for the zone and all devices in the zone to obtain the new temperature thresholds. > > This section of the ACPI specification tells me that we need to evaluate the _SCP control method of all ACPI thermal zones > at the same time, yet section 11.4.13. tells me that each _SCP control methods belongs to the individual thermal zone. > > The reason why i am concerned by this is because Windows adheres to section 11.1.2.1. and only exposes this setting > as a global tunable. This might cause device manufacturers to depend on this behavior and lead to strange things > should two thermal zones have different _SCP settings. > > I will ask the UEFI mailing list which behavior is expected by the ACPI specification. Until then i suggest that > we put this patch series on hold. Sure, no problem. Please resend it when you think it is good to go. Thanks!
