Microsoft in Windows 11 22H2 introduced a new ACPI Device Specific Method (DSM) “Turn On Display” notification that the Linux 7.0 kernel will be adding support for in dealing with some otherwise problematic laptop behavior.
Queued up into the Linux power management subsystem’s “linux-next” Git branch ahead of the upcoming Linux 6.20~7.0 kernel cycle is support in the s2idle driver for invoking the Microsoft Turn On Display DSM. Microsoft’s documentation describes the Turn On Display / Function 9 notification as being used to signal during resume time from modern standby when the intent is to turn on the system’s display.
Why this is important now is that some laptop firmware are beginning to expect this ACPI DSM method to be called on resume for proper handling. Leading to it being added to the Linux kernel’s s2idle code now is this bug report from August 2025 over a Lenovo Yoga Slim laptop seeing its fans completely stop working after a suspend/resume cycle and ultimately to overheating issues:
“After resuming from suspend, the laptop’s cooling fans do not reactivate regardless of CPU temperature or system load. This leads to CPU temperatures reaching 95 degrees Celsius during normal tasks, creating a safety hazard. The issue is 100% reproducible and occurs on multiple kernel versions. Only a complete reboot restores fan functionality. The same hardware works correctly under Windows.”
After months without any luck figuring out why this behavior was happening for this Lenovo Yoga laptop under Linux, last month it was discovered to be over this Turn On Display ACPI method and it not being called under Linux.
Jakob Riemenschneider explained in the queued patch:
“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.”
Supporting this then addresses the fan/thermal issues on the Lenovo Yoga laptop. With this behavior appearing so far on at least one laptop with a bug report, chances are other models are out there that may face similar issues under Linux with current kernels or other quirky behavior in being tailored around the Function 9 _DSM for powering them back up. With this DSM function being added three years ago in Windows 11 22H2, this support may also become more important/expected with future hardware/firmware too.
