[PATCH 1/1] PM: ACPI: reboot: Use S5 for reboot

[Kai-Heng Feng]

BugLink: https://bugs.launchpad.net/bugs/1904225

After reboot, it's not possible to use hotkeys to enter BIOS setup
and boot menu on some HP laptops.

BIOS folks identified the root cause is the missing _PTS call, and
BIOS is expecting _PTS to do proper reset.

Using S5 for reboot is default behavior under Windows, "A full
shutdown (S5) occurs when a system restart is requested" [1], so
let's do the same here.

[1] https://docs.microsoft.com/en-us/windows/win32/power/system-power-states

Signed-off-by: Kai-Heng Feng <kai.heng.feng at canonical.com>
[ rjw: Subject edit ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki at intel.com>
(cherry picked from commit d60cd06331a3566d3305b3c7b566e79edf4e2095 linux-next)
Signed-off-by: Kai-Heng Feng <kai.heng.feng at canonical.com>
---
 kernel/reboot.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/reboot.c b/kernel/reboot.c
index e7b78d5ae1ab..7e5aa1f78693 100644
--- a/kernel/reboot.c
+++ b/kernel/reboot.c
@@ -244,6 +244,8 @@ void migrate_to_reboot_cpu(void)
 void kernel_restart(char *cmd)
 {
 	kernel_restart_prepare(cmd);
+	if (pm_power_off_prepare)
+		pm_power_off_prepare();
 	migrate_to_reboot_cpu();
 	syscore_shutdown();
 	if (!cmd)
-- 
2.28.0