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

[Rafael J. Wysocki]

From: Rafael J. Wysocki <r...@sisk.pl>

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 and modify
acpi_power_transition() to avoid accessing power resources for
ACPI_STATE_D3_COLD, because they don't exist.

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 <rocko...@hotmail.com>
Reported-by: Cristian Rodríguez <crrod...@opensuse.org>
Reported-and-tested-by: Peter <leken...@gmail.com>
Signed-off-by: Rafael J. Wysocki <r...@sisk.pl>
---

Hi Linus,

Could you please take this one directly? It fixes obvious bugs and
makes pci_set_power_state(PCI_D3hot) work the same way as it did in
v3.3 and before, which is quite a big deal IMO.

Thanks,
Rafael

---
drivers/acpi/bus.c | 4 ++++
drivers/acpi/power.c | 9 ++++++---
drivers/acpi/scan.c | 4 ++++
drivers/pci/pci-acpi.c | 2 +-
4 files changed, 15 insertions(+), 4 deletions(-)

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
@@ -250,6 +250,10 @@ static int __acpi_bus_set_power(struct a
return -ENODEV;
}

+ /* For D3cold we should execute _PS3, not _PS4. */
+ if (state == ACPI_STATE_D3_COLD)
+ object_name[3] = '3';
+
/*
* Transition Power
* ----------------
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;
Index: linux/drivers/acpi/power.c
===================================================================
--- linux.orig/drivers/acpi/power.c
+++ linux/drivers/acpi/power.c
@@ -660,7 +660,7 @@ int acpi_power_on_resources(struct acpi_

int acpi_power_transition(struct acpi_device *device, int state)
{
- int result;
+ int result = 0;

if (!device || (state < ACPI_STATE_D0) || (state > ACPI_STATE_D3_COLD))
return -EINVAL;
@@ -679,8 +679,11 @@ int acpi_power_transition(struct acpi_de
* (e.g. so the device doesn't lose power while transitioning). Then,
* we dereference all power resources used in the current list.
*/
- result = acpi_power_on_list(&device->power.states[state].resources);
- if (!result)
+ if (state < ACPI_STATE_D3_COLD)
+ result = acpi_power_on_list(
+ &device->power.states[state].resources);
+
+ if (!result && device->power.state < ACPI_STATE_D3_COLD)
acpi_power_off_list(
&device->power.states[device->power.state].resources);

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[Cristian Rodríguez]

Ok, tested this one in the affected box, it works.

echo OFF > /sys/kernel/debug/vgaswitcheroo/switch
[ 77.436767] VGA switcheroo: switched nouveau off
[ 77.437004] [drm] nouveau 0000:01:00.0: Disabling display...
[ 77.437110] [drm] nouveau 0000:01:00.0: Disabling fbcon...
[ 77.437113] [drm] nouveau 0000:01:00.0: Unpinning framebuffer(s)...
[ 77.437157] [drm] nouveau 0000:01:00.0: Evicting buffers...
[ 77.439175] [drm] nouveau 0000:01:00.0: Idling channels...
[ 77.439316] [drm] nouveau 0000:01:00.0: Suspending GPU objects...
[ 77.771133] [drm] nouveau 0000:01:00.0: And we're gone!
[ 78.082258] nouveau 0000:01:00.0: power state changed by ACPI to D3

laptop's fan is silent again :-) , thanks for fixing it !