From: Rafael J. Wysocki rafael.j.wysocki@intel.com
[ Upstream commit c10383e8ddf4810b9a5c1595404c2724d925a0a6 ]
On some systems the ACPI namespace contains device objects that are not used in certain configurations of the system. If they start off in the D0 power state configuration, they will stay in it until the system reboots, because of the lack of any mechanism possibly causing their configuration to change. If that happens, they may prevent some power resources from being turned off or generally they may prevent the platform from getting into the deepest low-power states thus causing some energy to be wasted.
Address this issue by changing the configuration of unused ACPI device objects to the D3cold power state one after carrying out the ACPI-based enumeration of devices.
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=214091 Link: https://lore.kernel.org/linux-acpi/20211007205126.11769-1-mario.limonciello@... Reported-by: Mario Limonciello mario.limonciello@amd.com Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Tested-by: Mario Limonciello mario.limonciello@amd.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/acpi/glue.c | 25 +++++++++++++++++++++++++ drivers/acpi/internal.h | 1 + drivers/acpi/scan.c | 6 ++++++ 3 files changed, 32 insertions(+)
diff --git a/drivers/acpi/glue.c b/drivers/acpi/glue.c index fce3f3bba714a..3fd1713f1f626 100644 --- a/drivers/acpi/glue.c +++ b/drivers/acpi/glue.c @@ -363,3 +363,28 @@ int acpi_platform_notify(struct device *dev, enum kobject_action action) } return 0; } + +int acpi_dev_turn_off_if_unused(struct device *dev, void *not_used) +{ + struct acpi_device *adev = to_acpi_device(dev); + + /* + * Skip device objects with device IDs, because they may be in use even + * if they are not companions of any physical device objects. + */ + if (adev->pnp.type.hardware_id) + return 0; + + mutex_lock(&adev->physical_node_lock); + + /* + * Device objects without device IDs are not in use if they have no + * corresponding physical device objects. + */ + if (list_empty(&adev->physical_node_list)) + acpi_device_set_power(adev, ACPI_STATE_D3_COLD); + + mutex_unlock(&adev->physical_node_lock); + + return 0; +} diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h index d91b560e88674..8fbdc172864b0 100644 --- a/drivers/acpi/internal.h +++ b/drivers/acpi/internal.h @@ -117,6 +117,7 @@ bool acpi_device_is_battery(struct acpi_device *adev); bool acpi_device_is_first_physical_node(struct acpi_device *adev, const struct device *dev); int acpi_bus_register_early_device(int type); +int acpi_dev_turn_off_if_unused(struct device *dev, void *not_used);
/* -------------------------------------------------------------------------- Device Matching and Notification diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c index b24513ec3fae1..ae9464091f1b1 100644 --- a/drivers/acpi/scan.c +++ b/drivers/acpi/scan.c @@ -2560,6 +2560,12 @@ int __init acpi_scan_init(void) } }
+ /* + * Make sure that power management resources are not blocked by ACPI + * device objects with no users. + */ + bus_for_each_dev(&acpi_bus_type, NULL, NULL, acpi_dev_turn_off_if_unused); + acpi_turn_off_unused_power_resources();
acpi_scan_initialized = true;