Commit 42787ed7 authored Aug 01, 2019 by Rafael J. Wysocki

ACPI: PM: Fix regression in acpi_device_set_power()



Commit f850a48a ("ACPI: PM: Allow transitions to D0 to occur in
special cases") overlooked the fact that acpi_power_transition() may
change the power.state value for the target device and if that
happens, it may confuse acpi_device_set_power() and cause it to
omit the _PS0 evaluation which on some systems is necessary to
change power states of devices from low-power to D0.

Fix that by saving the current value of power.state for the
target device before passing it to acpi_power_transition() and
using the saved value in a subsequent check.

Fixes: f850a48a ("ACPI: PM: Allow transitions to D0 to occur in special cases")
Reported-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Reported-by: Mario Limonciello <mario.limonciello@dell.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Tested-by: Mario Limonciello <mario.limonciello@dell.com>

parent 609488bc

drivers/acpi/device_pm.c

+3 −1

Original line number	Original line	Diff line number	Diff line
	@@ -232,13 +232,15 @@ int acpi_device_set_power(struct acpi_device *device, int state)
	if (device->power.flags.power_resources)		if (device->power.flags.power_resources)
	result = acpi_power_transition(device, target_state);		result = acpi_power_transition(device, target_state);
	} else {		} else {
			int cur_state = device->power.state;

	if (device->power.flags.power_resources) {		if (device->power.flags.power_resources) {
	result = acpi_power_transition(device, ACPI_STATE_D0);		result = acpi_power_transition(device, ACPI_STATE_D0);
	if (result)		if (result)
	goto end;		goto end;
	}		}

	if (device->power.state == ACPI_STATE_D0) {		if (cur_state == ACPI_STATE_D0) {
	int psc;		int psc;

	/* Nothing to do here if _PSC is not present. */		/* Nothing to do here if _PSC is not present. */

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