[v2,1/2] ACPI: scan: Turn off unused power resources during initialization
diff mbox series

Message ID 9860889.nUPlyArG6x@kreacher
State New, archived
Headers show
  • ACPI: scan: Turn off unused power resources during initialization
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Commit Message

Rafael J. Wysocki March 18, 2021, 6:25 p.m. UTC
From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

It is reported that on certain platforms there are power resources
that are not associated with any devices physically present in the
platform.  Those power resources are expected to be turned off by
the OS in accordance with the ACPI specification (section 7.3 of
ACPI 6.4) which currently is not done by Linux and that may lead
to obscure issues.

For instance, leaving those power resources in the "on" state may
prevent the platform from reaching the lowest power state in
suspend-to-idle which leads to excessive power draw.

For this reason, turn all of the unused ACPI power resources off
at the end of the initial namespace scan for devices in analogy with
resume from suspend-to-RAM.

Link: https://uefi.org/specs/ACPI/6.4/07_Power_and_Performance_Mgmt/device-power-management-objects.html
Reported-by: David Box <david.e.box@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

-> v2: Expand the changelog somewhat and make it build with CONFIG_PM_SLEEP

 drivers/acpi/internal.h |    1 +
 drivers/acpi/power.c    |    2 +-
 drivers/acpi/scan.c     |    2 ++
 drivers/acpi/sleep.h    |    1 -
 4 files changed, 4 insertions(+), 2 deletions(-)

diff mbox series

Index: linux-pm/drivers/acpi/internal.h
--- linux-pm.orig/drivers/acpi/internal.h
+++ linux-pm/drivers/acpi/internal.h
@@ -139,6 +139,7 @@  int acpi_device_sleep_wake(struct acpi_d
 int acpi_power_get_inferred_state(struct acpi_device *device, int *state);
 int acpi_power_on_resources(struct acpi_device *device, int state);
 int acpi_power_transition(struct acpi_device *device, int state);
+void acpi_turn_off_unused_power_resources(void);
 /* --------------------------------------------------------------------------
                               Device Power Management
Index: linux-pm/drivers/acpi/scan.c
--- linux-pm.orig/drivers/acpi/scan.c
+++ linux-pm/drivers/acpi/scan.c
@@ -2360,6 +2360,8 @@  int __init acpi_scan_init(void)
+	acpi_turn_off_unused_power_resources();
 	acpi_scan_initialized = true;
Index: linux-pm/drivers/acpi/sleep.h
--- linux-pm.orig/drivers/acpi/sleep.h
+++ linux-pm/drivers/acpi/sleep.h
@@ -8,7 +8,6 @@  extern struct list_head acpi_wakeup_devi
 extern struct mutex acpi_device_lock;
 extern void acpi_resume_power_resources(void);
-extern void acpi_turn_off_unused_power_resources(void);
 static inline acpi_status acpi_set_waking_vector(u32 wakeup_address)
Index: linux-pm/drivers/acpi/power.c
--- linux-pm.orig/drivers/acpi/power.c
+++ linux-pm/drivers/acpi/power.c
@@ -996,6 +996,7 @@  void acpi_resume_power_resources(void)
 void acpi_turn_off_unused_power_resources(void)
@@ -1025,4 +1026,3 @@  void acpi_turn_off_unused_power_resource