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[Update][PATCH] ACPI / PCI / PM: Fix device PM regression related to D3hot/D3cold

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From: Rafael J. Wysocki <rjw@xxxxxxx>
Subject: ACPI / PCI / PM: Fix device PM regression related to D3hot/D3cold

Commit 1cc0c998fdf2cb665d625fb565a0d6db5c81c639 (ACPI: Fix D3hot
v D3cold confusion) introduced a bug in __acpi_bus_set_power() and
changed the behavior of acpi_pci_set_power_state() in such a way that
it generally doesn't work as expected if PCI_D3hot is passed to it
as the second argument.

First off, if ACPI_STATE_D3 (equal to ACPI_STATE_D3_COLD) is passed
to __acpi_bus_set_power() and the explicit_set flag is set for the
D3cold state, the function will try to execute AML method called
"_PS4", which doesn't exist.

Fix this by adding a check to ensure that the name of the AML method
to execute for transitions to ACPI_STATE_D3_COLD is correct in
__acpi_bus_set_power().  Also make sure that the explicit_set flag
for ACPI_STATE_D3_COLD will be set if _PS3 is present.

Second, if PCI_D3hot is passed to acpi_pci_set_power_state() as the
target state, the function will request a transition to
ACPI_STATE_D3_HOT instead of ACPI_STATE_D3.  However,
ACPI_STATE_D3_HOT is now only marked as supported if the _PR3 AML
method is defined for the given device, which is rare.  This causes
problems to happen on systems where devices were successfully put
into ACPI D3 by pci_set_power_state(PCI_D3hot) which doesn't work
now.  In particular, some unused graphics adapters are not turned
off as a result.

To fix this issue restore the old behavior of
acpi_pci_set_power_state(), which is to request a transition to
ACPI_STATE_D3 (equal to ACPI_STATE_D3_COLD) if either PCI_D3hot or
PCI_D3cold is passed to it as the argument.

This approach is not ideal, because generally power should not
be removed from devices if PCI_D3hot is the target power state,
but since this behavior is relied on, we have no choice but to
restore it at the moment and spend more time on designing a
better solution in the future.

References: https://bugzilla.kernel.org/show_bug.cgi?id=43228
Reported-by: rocko <rockorequin@xxxxxxxxxxx>
Reported-by: Cristian Rodríguez <crrodriguez@xxxxxxxxxxxx>
Reported-and-tested-by: Peter <lekensteyn@xxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rjw@xxxxxxx>
---

The previous patch was still insufficient due to the missing change
in drivers/acpi/scan.c.  Please test this one.

Rafael

---
 drivers/acpi/bus.c     |    4 ++++
 drivers/acpi/scan.c    |    4 ++++
 drivers/pci/pci-acpi.c |    2 +-
 3 files changed, 9 insertions(+), 1 deletion(-)

Index: linux/drivers/pci/pci-acpi.c
===================================================================
--- linux.orig/drivers/pci/pci-acpi.c
+++ linux/drivers/pci/pci-acpi.c
@@ -223,7 +223,7 @@ static int acpi_pci_set_power_state(stru
 		[PCI_D0] = ACPI_STATE_D0,
 		[PCI_D1] = ACPI_STATE_D1,
 		[PCI_D2] = ACPI_STATE_D2,
-		[PCI_D3hot] = ACPI_STATE_D3_HOT,
+		[PCI_D3hot] = ACPI_STATE_D3,
 		[PCI_D3cold] = ACPI_STATE_D3
 	};
 	int error = -EINVAL;
Index: linux/drivers/acpi/bus.c
===================================================================
--- linux.orig/drivers/acpi/bus.c
+++ linux/drivers/acpi/bus.c
@@ -273,6 +273,10 @@ static int __acpi_bus_set_power(struct a
 		}
 	} else {
 		if (device->power.states[state].flags.explicit_set) {
+			/* _PS3 should be executed for D3cold, not _PS4. */
+			if (state == ACPI_STATE_D3_COLD)
+				object_name[3] = '3';
+
 			status = acpi_evaluate_object(device->handle,
 						      object_name, NULL, NULL);
 			if (ACPI_FAILURE(status)) {
Index: linux/drivers/acpi/scan.c
===================================================================
--- linux.orig/drivers/acpi/scan.c
+++ linux/drivers/acpi/scan.c
@@ -908,6 +908,10 @@ static int acpi_bus_get_power_flags(stru
 	device->power.states[ACPI_STATE_D3].flags.valid = 1;
 	device->power.states[ACPI_STATE_D3].power = 0;
 
+	/* Set D3cold's explicit_set flag if _PS3 exists. */
+	if (device->power.states[ACPI_STATE_D3_HOT].flags.explicit_set)
+		device->power.states[ACPI_STATE_D3_COLD].flags.explicit_set = 1;
+
 	acpi_bus_init_power(device);
 
 	return 0;

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