Commit 7e4fdeaf authored Mar 18, 2021 by Rafael J. Wysocki

ACPI: power: Turn off unused power resources unconditionally

According to the ACPI specification (section 7.2.2 in ACPI 6.4), the
OS may evaluate the _OFF method of a power resource that is "off"
already [1], and in particular that can be done in the case of unused
power resources.

Accordingly, modify acpi_turn_off_unused_power_resources() to
evaluate the _OFF method for each of the unused power resources
unconditionally which may help to work around BIOS issues where the
return value of _STA for a power resource does not reflect the
actual state of the power resource [2].

Link: https://uefi.org/specs/ACPI/6.4/07_Power_and_Performance_Mgmt/declaring-a-power-resource-object.html#off # [1]
Link: https://lore.kernel.org/lkml/20210314000439.3138941-1-luzmaximilian@gmail.com/

 # [2]
Tested-by: Wendy Wang <wendy.wang@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

parent 4b9ee772

drivers/acpi/power.c

+1 −10

Original line number	Diff line number	Diff line
		@@ -1005,18 +1005,9 @@ void acpi_turn_off_unused_power_resources(void)
		mutex_lock(&power_resource_list_lock);

		list_for_each_entry_reverse(resource, &acpi_power_resource_list, list_node) {
		int result, state;

		mutex_lock(&resource->resource_lock);

		result = acpi_power_get_state(resource->device.handle, &state);
		if (result) {
		mutex_unlock(&resource->resource_lock);
		continue;
		}

		if (state == ACPI_POWER_RESOURCE_STATE_ON
		&& !resource->ref_count) {
		if (!resource->ref_count) {
		dev_info(&resource->device.dev, "Turning OFF\n");
		__acpi_power_off(resource);
		}