[PATCH] PM / reboot: Use S5 for reboot

[Kai-Heng Feng]

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@xxxxxxxxxxxxx>
---
 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)
-- 
2.17.1