PM / sleep / ACPI: Use the ACPI_FADT_LOW_POWER_S0 flag

Modify the ACPI system sleep support setup code to select
suspend-to-idle as the default system sleep state if the
ACPI_FADT_LOW_POWER_S0 flag is set in the FADT and the
default sleep state was not selected from the kernel command
line.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Mario Limonciello <mario.limonciello@dell.com>

diff --git a/Documentation/power/states.txt b/Documentation/power/states.txt
index 008ecb5..8a39ce4 100644 (file)
--- a/Documentation/power/states.txt
+++ b/Documentation/power/states.txt
@@ -35,7 +35,9 @@ only one way to cause the system to go into the Suspend-To-RAM state (write
 The default suspend mode (ie. the one to be used without writing anything into
 /sys/power/mem_sleep) is either "deep" (if Suspend-To-RAM is supported) or
 "s2idle", but it can be overridden by the value of the "mem_sleep_default"
-parameter in the kernel command line.
+parameter in the kernel command line.  On some ACPI-based systems, depending on
+the information in the FADT, the default may be "s2idle" even if Suspend-To-RAM
+is supported.
 
 The properties of all of the sleep states are described below.
 

diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
index deb0ff7..ce1855f 100644 (file)
--- a/drivers/acpi/sleep.c
+++ b/drivers/acpi/sleep.c
@@ -691,6 +691,14 @@ static void acpi_sleep_suspend_setup(void)
                if (acpi_sleep_state_supported(i))
                        sleep_states[i] = 1;
 
+       /*
+        * Use suspend-to-idle by default if ACPI_FADT_LOW_POWER_S0 is set and
+        * the default suspend mode was not selected from the command line.
+        */
+       if (acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0 &&
+           mem_sleep_default > PM_SUSPEND_MEM)
+               mem_sleep_default = PM_SUSPEND_FREEZE;
+
        suspend_set_ops(old_suspend_ordering ?
                &acpi_suspend_ops_old : &acpi_suspend_ops);
        freeze_set_ops(&acpi_freeze_ops);

diff --git a/include/linux/suspend.h b/include/linux/suspend.h
index d971837..0c729c3 100644 (file)
--- a/include/linux/suspend.h
+++ b/include/linux/suspend.h
@@ -194,6 +194,8 @@ struct platform_freeze_ops {
 };
 
 #ifdef CONFIG_SUSPEND
+extern suspend_state_t mem_sleep_default;
+
 /**
  * suspend_set_ops - set platform dependent suspend operations
  * @ops: The new suspend operations to set.

diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
index 15e6bae..f67ceb7 100644 (file)
--- a/kernel/power/suspend.c
+++ b/kernel/power/suspend.c
@@ -46,7 +46,7 @@ static const char * const mem_sleep_labels[] = {
 const char *mem_sleep_states[PM_SUSPEND_MAX];
 
 suspend_state_t mem_sleep_current = PM_SUSPEND_FREEZE;
-static suspend_state_t mem_sleep_default = PM_SUSPEND_MEM;
+suspend_state_t mem_sleep_default = PM_SUSPEND_MAX;
 
 unsigned int pm_suspend_global_flags;
 EXPORT_SYMBOL_GPL(pm_suspend_global_flags);
@@ -168,7 +168,7 @@ void suspend_set_ops(const struct platform_suspend_ops *ops)
        }
        if (valid_state(PM_SUSPEND_MEM)) {
                mem_sleep_states[PM_SUSPEND_MEM] = mem_sleep_labels[PM_SUSPEND_MEM];
-               if (mem_sleep_default == PM_SUSPEND_MEM)
+               if (mem_sleep_default >= PM_SUSPEND_MEM)
                        mem_sleep_current = PM_SUSPEND_MEM;
        }