ACPI PM: Restore the 2.6.24 suspend ordering

Some time ago it turned out that our suspend code ordering broke some
NVidia-based systems that hung if _PTS was executed with one of the PCI
devices, specifically a USB controller, in a low power state.

Then, it was noticed that the suspend code ordering was not compliant
with ACPI 1.0, although it was compliant with ACPI 2.0 (and later), and
it was argued that the code had to be changed for that reason (ref.
http://bugzilla.kernel.org/show_bug.cgi?id=9528).

So we did, but evidently we did wrong, because it's now turning out that
some systems have been broken by this change. Refs:
http://bugzilla.kernel.org/show_bug.cgi?id=10340
https://bugzilla.novell.com/show_bug.cgi?id=374217#c16

[ I said at that time that something like this might happend, but the
majority of people involved thought that it was improbable due to the
necessity to preserve the compliance of hardware with ACPI 1.0. ]

This actually is a quite serious regression from 2.6.24.

Moreover, the ACPI 1.0 ordering of suspend code introduced another issue
that I have only noticed recently. Namely, if the suspend of one of
devices fails, the already suspended devices will be resumed without
executing _WAK before, which leads to problems on some systems (for
example, in such situations thermal management is broken on my HP
nx6325). Consequently, it also breaks suspend debugging on the affected
systems.

Note also, that the requirement to execute _PTS before suspending
devices does not really make sense, because the device in question may
be put into a low power state at run time for a reason unrelated to a
system-wide suspend.

For the reasons outlined above, the change of the suspend ordering
should be reverted, which is done by the patch below.

[ Felix Möller: "I am the reporter from the original Novell Bug:

https://bugzilla.novell.com/show_bug.cgi?id=374217

I just tried current git head (two hours ago) with the patch (the one
from the beginning of this thread) from Rafael and without it. With
the patch my MacBook does suspend without it does not." ]

Signed-off-by: Rafael J. Wysocki <[e-mail]>
Tested-by: Felix Möller <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

Documentation/kernel-parameters.txt

···
 	acpi_irq_isa=	[HW,ACPI] If irq_balance, mark listed IRQs used by ISA
 			Format: <irq>,<irq>...
 
-	acpi_new_pts_ordering [HW,ACPI]
-			Enforce the ACPI 2.0 ordering of the _PTS control
-			method wrt putting devices into low power states
-			default: pre ACPI 2.0 ordering of _PTS
-
 	acpi_no_auto_ssdt	[HW,ACPI] Disable automatic loading of SSDT
 
 	acpi_os_name=	[HW,ACPI] Tell ACPI BIOS the name of the OS

drivers/acpi/sleep/main.c

···
 
 #ifdef CONFIG_PM_SLEEP
 static u32 acpi_target_sleep_state = ACPI_STATE_S0;
-static bool acpi_sleep_finish_wake_up;
-
-/*
- * ACPI 2.0 and later want us to execute _PTS after suspending devices, so we
- * allow the user to request that behavior by using the 'acpi_new_pts_ordering'
- * kernel command line option that causes the following variable to be set.
- */
-static bool new_pts_ordering;
-
-static int __init acpi_new_pts_ordering(char *str)
-{
-	new_pts_ordering = true;
-	return 1;
-}
-__setup("acpi_new_pts_ordering", acpi_new_pts_ordering);
 #endif
 
 static int acpi_sleep_prepare(u32 acpi_state)
···
 
 	if (sleep_states[acpi_state]) {
 		acpi_target_sleep_state = acpi_state;
-		if (new_pts_ordering)
-			return 0;
-
-		error = acpi_sleep_prepare(acpi_state);
-		if (error)
-			acpi_target_sleep_state = ACPI_STATE_S0;
-		else
-			acpi_sleep_finish_wake_up = true;
 	} else {
 		printk(KERN_ERR "ACPI does not support this state: %d\n",
 			pm_state);
···
 
 static int acpi_pm_prepare(void)
 {
-	if (new_pts_ordering) {
-		int error = acpi_sleep_prepare(acpi_target_sleep_state);
+	int error = acpi_sleep_prepare(acpi_target_sleep_state);
 
-		if (error) {
-			acpi_target_sleep_state = ACPI_STATE_S0;
-			return error;
-		}
-		acpi_sleep_finish_wake_up = true;
+	if (error) {
+		acpi_target_sleep_state = ACPI_STATE_S0;
+		return error;
 	}
 
 	return ACPI_SUCCESS(acpi_hw_disable_all_gpes()) ? 0 : -EFAULT;
···
 	acpi_set_firmware_waking_vector((acpi_physical_address) 0);
 
 	acpi_target_sleep_state = ACPI_STATE_S0;
-	acpi_sleep_finish_wake_up = false;
 
 #ifdef CONFIG_X86
 	if (init_8259A_after_S1) {
···
 static void acpi_pm_end(void)
 {
 	/*
-	 * This is necessary in case acpi_pm_finish() is not called directly
-	 * during a failing transition to a sleep state.
+	 * This is necessary in case acpi_pm_finish() is not called during a
+	 * failing transition to a sleep state.
 	 */
-	if (acpi_sleep_finish_wake_up)
-		acpi_pm_finish();
+	acpi_target_sleep_state = ACPI_STATE_S0;
 }
 
 static int acpi_pm_state_valid(suspend_state_t pm_state)
···
 #ifdef CONFIG_HIBERNATION
 static int acpi_hibernation_begin(void)
 {
-	int error;
-
 	acpi_target_sleep_state = ACPI_STATE_S4;
-	if (new_pts_ordering)
-		return 0;
 
-	error = acpi_sleep_prepare(ACPI_STATE_S4);
-	if (error)
-		acpi_target_sleep_state = ACPI_STATE_S0;
-	else
-		acpi_sleep_finish_wake_up = true;
-
-	return error;
+	return 0;
 }
 
 static int acpi_hibernation_prepare(void)
 {
-	if (new_pts_ordering) {
-		int error = acpi_sleep_prepare(ACPI_STATE_S4);
+	int error = acpi_sleep_prepare(ACPI_STATE_S4);
 
-		if (error) {
-			acpi_target_sleep_state = ACPI_STATE_S0;
-			return error;
-		}
-		acpi_sleep_finish_wake_up = true;
+	if (error) {
+		acpi_target_sleep_state = ACPI_STATE_S0;
+		return error;
 	}
 
 	return ACPI_SUCCESS(acpi_hw_disable_all_gpes()) ? 0 : -EFAULT;
···
 	acpi_set_firmware_waking_vector((acpi_physical_address) 0);
 
 	acpi_target_sleep_state = ACPI_STATE_S0;
-	acpi_sleep_finish_wake_up = false;
 }
 
 static void acpi_hibernation_end(void)
 {
 	/*
 	 * This is necessary in case acpi_hibernation_finish() is not called
-	 * directly during a failing transition to the sleep state.
+	 * during a failing transition to the sleep state.
 	 */
-	if (acpi_sleep_finish_wake_up)
-		acpi_hibernation_finish();
+	acpi_target_sleep_state = ACPI_STATE_S0;
 }
 
 static int acpi_hibernation_pre_restore(void)