[PATCH v2 2/5] acpi/x86: s2idle: handle Display On/Off calls outside of suspend sequence

[Antheas Kapenekakis <lkml@antheas.dev>]

Currently, the Display On/Off calls are handled within the suspend
sequence, which is a deviation from Windows. This causes issues with
certain devices, where the notification interacts with a USB device
that expects the kernel to be fully awake.

This patch calls the Display On/Off callbacks before entering the suspend
sequence, which fixes this issue. In addition, it opens the possibility
of modelling a state such as "Screen Off" that mirrors Windows, as the
callbacks will be accessible and validated to work outside of the
suspend sequence.

Suggested-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Antheas Kapenekakis <lkml@antheas.dev>
---
 kernel/power/suspend.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
index c527dc0ae5ae..610f8ecaeebd 100644
--- a/kernel/power/suspend.c
+++ b/kernel/power/suspend.c
@@ -589,6 +589,13 @@ static int enter_state(suspend_state_t state)
 	if (state == PM_SUSPEND_TO_IDLE)
 		s2idle_begin();
 
+	/*
+	 * Linux does not have the concept of a "Screen Off" state, so call
+	 * the platform functions for Display On/Off prior to the suspend
+	 * sequence, mirroring Windows which calls them outside of it as well.
+	 */
+	platform_suspend_display_off();
+
 	if (sync_on_suspend_enabled) {
 		trace_suspend_resume(TPS("sync_filesystems"), 0, true);
 		ksys_sync_helper();
@@ -616,6 +623,8 @@ static int enter_state(suspend_state_t state)
 	suspend_finish();
  Unlock:
 	mutex_unlock(&system_transition_mutex);
+
+	platform_suspend_display_on();
 	return error;
 }
 
-- 
2.46.1