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-rw-r--r--Documentation/admin-guide/kernel-parameters.txt12
-rw-r--r--kernel/power/main.c9
2 files changed, 21 insertions, 0 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index f1f2c0874da9..06beacf208de 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5000,6 +5000,18 @@
that number, otherwise (e.g., 'pmu_override=on'), MMCR1
remains 0.
+ pm_async= [PM]
+ Format: off
+ This parameter sets the initial value of the
+ /sys/power/pm_async sysfs knob at boot time.
+ If set to "off", disables asynchronous suspend and
+ resume of devices during system-wide power transitions.
+ This can be useful on platforms where device
+ dependencies are not well-defined, or for debugging
+ power management issues. Asynchronous operations are
+ enabled by default.
+
+
pm_debug_messages [SUSPEND,KNL]
Enable suspend/resume debug messages during boot up.
diff --git a/kernel/power/main.c b/kernel/power/main.c
index 3d484630505a..3cf2d7e72567 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -8,6 +8,7 @@
#include <linux/acpi.h>
#include <linux/export.h>
+#include <linux/init.h>
#include <linux/kobject.h>
#include <linux/string.h>
#include <linux/pm-trace.h>
@@ -112,6 +113,14 @@ int pm_notifier_call_chain(unsigned long val)
/* If set, devices may be suspended and resumed asynchronously. */
int pm_async_enabled = 1;
+static int __init pm_async_setup(char *str)
+{
+ if (!strcmp(str, "off"))
+ pm_async_enabled = 0;
+ return 1;
+}
+__setup("pm_async=", pm_async_setup);
+
static ssize_t pm_async_show(struct kobject *kobj, struct kobj_attribute *attr,
char *buf)
{