linux-kernel - [PATCH] ACPI: x86: s2idle: Invoke Microsoft

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Message-ID: <20260107154015.322698-1-jriemenschne@student.ethz.ch>
Date: Wed,  7 Jan 2026 16:40:15 +0100
From: Jakob Riemenschneider <riemenschneiderjakob@...il.com>
To: rafael@...nel.org,
	lenb@...nel.org
Cc: linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] ACPI: x86: s2idle: Invoke Microsoft _DSM Function 9 (Turn On Display)

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,
improving resume latency on supported OEM designs. Without this call,
some devices may remain in a throttled power state longer than necessary
during resume.

This patch defines the new function index (ACPI_LPS0_MS_DISPLAY_ON) and
invokes it in acpi_s2idle_restore_early_lps0() immediately after the
screen-on notification, provided the firmware supports the function in
its mask.

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
Signed-off-by: Jakob Riemenschneider <jriemenschne@...dent.ethz.ch>
---
 drivers/acpi/x86/s2idle.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/x86/s2idle.c b/drivers/acpi/x86/s2idle.c
index 6d4d06236..4ce4cc8a0 100644
--- a/drivers/acpi/x86/s2idle.c
+++ b/drivers/acpi/x86/s2idle.c
@@ -45,6 +45,7 @@ static const struct acpi_device_id lps0_device_ids[] = {
 #define ACPI_LPS0_EXIT		6
 #define ACPI_LPS0_MS_ENTRY      7
 #define ACPI_LPS0_MS_EXIT       8
+#define ACPI_LPS0_MS_DISPLAY_ON 9
 
 /* AMD */
 #define ACPI_LPS0_DSM_UUID_AMD      "e3f32452-febc-43ce-9039-932122d37721"
@@ -352,6 +353,8 @@ static const char *acpi_sleep_dsm_state_to_str(unsigned int state)
 			return "lps0 ms entry";
 		case ACPI_LPS0_MS_EXIT:
 			return "lps0 ms exit";
+		case ACPI_LPS0_MS_DISPLAY_ON:
+			return "lps0 ms display on";
 		}
 	} else {
 		switch (state) {
@@ -618,9 +621,14 @@ static void acpi_s2idle_restore_early_lps0(void)
 	}
 
 	/* Screen on */
-	if (lps0_dsm_func_mask_microsoft > 0)
+	if (lps0_dsm_func_mask_microsoft > 0) {
 		acpi_sleep_run_lps0_dsm(ACPI_LPS0_SCREEN_ON,
 				lps0_dsm_func_mask_microsoft, lps0_dsm_guid_microsoft);
+				/* Modern Turn Display On */
+		acpi_sleep_run_lps0_dsm(ACPI_LPS0_MS_DISPLAY_ON,
+				lps0_dsm_func_mask_microsoft, lps0_dsm_guid_microsoft);
+	}
+
 	if (lps0_dsm_func_mask > 0)
 		acpi_sleep_run_lps0_dsm(acpi_s2idle_vendor_amd() ?
 					ACPI_LPS0_SCREEN_ON_AMD :
-- 
2.52.0