From c10383e8ddf4810b9a5c1595404c2724d925a0a6 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Sat, 9 Oct 2021 16:22:09 +0200 Subject: [PATCH] ACPI: scan: Release PM resources blocked by unused objects 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@amd.com/ Reported-by: Mario Limonciello Signed-off-by: Rafael J. Wysocki Tested-by: Mario Limonciello --- 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 7a33a6d..1cfafa2 100644 --- a/drivers/acpi/glue.c +++ b/drivers/acpi/glue.c @@ -340,3 +340,28 @@ void acpi_device_notify_remove(struct device *dev) acpi_unbind_one(dev); } + +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 d91b560..8fbdc17 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 5b54c80..770b824 100644 --- a/drivers/acpi/scan.c +++ b/drivers/acpi/scan.c @@ -2559,6 +2559,12 @@ 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; -- 2.7.4