Re: [PATCH v2] ACPI: x86: s2idle: Invoke Microsoft _DSM Function 9 (Turn On Display)

[Rafael J. Wysocki]

On Tue, Jan 27, 2026 at 9:06 PM Antheas Kapenekakis <lkml@xxxxxxxxxxx> wrote:
>
> On Tue, 27 Jan 2026 at 21:01, Jakob Riemenschneider
> <riemenschneiderjakob@xxxxxxxxx> wrote:
> >
> > Windows 11, version 22H2 introduced a new function index (Function 9) to
> > the Microsoft LPS0 _DSM, titled "Turn On Display Notification".
> >
> > According to Microsoft documentation, this function signals to the system
> > firmware that the OS intends to turn on the display when exiting Modern
> > Standby. This allows the firmware to release Power Limits (PLx) earlier.
> >
> > Crucially, this patch fixes a functional issue observed on the Lenovo Yoga
> > Slim 7i Aura (15ILL9), where system fans and keyboard backlights fail to
> > resume after suspend. Investigation linked shows the EC on this device
> > turns off these components during sleep but requires the Function 9
> > notification to wake them up again.
> >
> > This patch defines the new function index (ACPI_MS_TURN_ON_DISPLAY) and
> > invokes it in acpi_s2idle_restore_early_lps0(). The execution order is
> > updated to match the logic of an "intent" signal:
> >
> > 1. LPS0 Exit (Function 6)
> > 2. Turn On Display Intent (Function 9)
> > 3. Modern Standby Exit (Function 8)
> > 4. Screen On (Function 4)
> >
> > Invoking Function 9 before the Modern Standby Exit ensures the firmware
> > has time to restore power rails and functionality (like fans) before the
> > software fully exits the sleep state.
> >
> > Link: https://learn.microsoft.com/en-us/windows-hardware/design/device-experiences/modern-standby-firmware-notifications#turn-on-display-notification-function-9
> > Link: https://bugzilla.kernel.org/show_bug.cgi?id=220505
> > Suggested-by: Antheas Kapenekakis <antheas@xxxxxxxxxxx>
>
> LGTM, no need for rby, sby covers it.
>
> Consider closes + reported by from bugzilla if there is a V3, I
> typically use lkml@xxxxxxxxxxx but that is small.
>
> I will defer to Rafael now

Applied as 6.20 material (changed Link: to Closes: for the BZ link), thanks!