From: Rafael J. Wysocki <rjw@xxxxxxx>
Add sysfs attribute /sys/power/pm_async allowing the user space to
disable/enable asynchronous suspend/resume of devices.
Signed-off-by: Rafael J. Wysocki <rjw@xxxxxxx>
---
Documentation/ABI/testing/sysfs-power | 13 +++++++++++++
drivers/base/power/main.c | 7 ++++---
drivers/base/power/power.h | 6 +++---
kernel/power/main.c | 31 ++++++++++++++++++++++++++++++-
4 files changed, 50 insertions(+), 7 deletions(-)
Index: linux-2.6/kernel/power/main.c
===================================================================
--- linux-2.6.orig/kernel/power/main.c
+++ linux-2.6/kernel/power/main.c
@@ -44,6 +44,32 @@ int pm_notifier_call_chain(unsigned long
== NOTIFY_BAD) ? -EINVAL : 0;
}
+/* If set, devices may be suspended and resumed asynchronously. */
+int pm_async_enabled = 1;
+
+static ssize_t pm_async_show(struct kobject *kobj, struct kobj_attribute *attr,
+ char *buf)
+{
+ return sprintf(buf, "%d\n", pm_async_enabled);
+}
+
+static ssize_t pm_async_store(struct kobject *kobj, struct kobj_attribute *attr,
+ const char *buf, size_t n)
+{
+ unsigned long val;
+
+ if (strict_strtoul(buf, 10, &val))
+ return -EINVAL;
+
+ if (val > 1)
+ return -EINVAL;
+
+ pm_async_enabled = val;
+ return n;
+}
+
+power_attr(pm_async);
+
#ifdef CONFIG_PM_DEBUG
int pm_test_level = TEST_NONE;
@@ -208,9 +234,12 @@ static struct attribute * g[] = {
#ifdef CONFIG_PM_TRACE
&pm_trace_attr.attr,
#endif
-#if defined(CONFIG_PM_SLEEP) && defined(CONFIG_PM_DEBUG)
+#ifdef CONFIG_PM_SLEEP
+ &pm_async_attr.attr,
+#ifdef CONFIG_PM_DEBUG
&pm_test_attr.attr,
#endif
+#endif
NULL,
};
Index: linux-2.6/drivers/base/power/power.h
===================================================================
--- linux-2.6.orig/drivers/base/power/power.h
+++ linux-2.6/drivers/base/power/power.h
@@ -12,10 +12,10 @@ static inline void pm_runtime_remove(str
#ifdef CONFIG_PM_SLEEP
-/*
- * main.c
- */
+/* kernel/power/main.c */
+extern int pm_async_enabled;
+/* drivers/base/power/main.c */
extern struct list_head dpm_list; /* The active device list */
static inline struct device *to_device(struct list_head *entry)
Index: linux-2.6/drivers/base/power/main.c
===================================================================
--- linux-2.6.orig/drivers/base/power/main.c
+++ linux-2.6/drivers/base/power/main.c
@@ -201,7 +201,7 @@ static void dpm_wait(struct device *dev,
if (!dev)
return;
- if (async || dev->power.async_suspend)
+ if (async || (pm_async_enabled && dev->power.async_suspend))
wait_for_completion(&dev->power.completion);
}
@@ -563,7 +563,8 @@ static int device_resume(struct device *
{
INIT_COMPLETION(dev->power.completion);
- if (dev->power.async_suspend && !pm_trace_is_enabled()) {
+ if (pm_async_enabled && dev->power.async_suspend
+ && !pm_trace_is_enabled()) {
get_device(dev);
async_schedule(async_resume, dev);
return 0;
@@ -867,7 +868,7 @@ static int device_suspend(struct device
{
INIT_COMPLETION(dev->power.completion);
- if (dev->power.async_suspend) {
+ if (pm_async_enabled && dev->power.async_suspend) {
get_device(dev);
async_schedule(async_suspend, dev);
return 0;
Index: linux-2.6/Documentation/ABI/testing/sysfs-power
===================================================================
--- linux-2.6.orig/Documentation/ABI/testing/sysfs-power
+++ linux-2.6/Documentation/ABI/testing/sysfs-power
@@ -101,3 +101,16 @@ Description:
CAUTION: Using it will cause your machine's real-time (CMOS)
clock to be set to a random invalid time after a resume.
+
+What: /sys/power/pm_async
+Date: January 2009
+Contact: Rafael J. Wysocki <rjw@xxxxxxx>
+Description:
+ The /sys/power/pm_async file controls the switch allowing the
+ user space to enable or disable asynchronous suspend and resume
+ of devices. If enabled, this feature will cause some device
+ drivers' suspend and resume callbacks to be executed in parallel
+ with each other and with the main suspend thread. It is enabled
+ if this file contains "1", which is the default. It may be
+ disabled by writing "0" to this file, in which case all devices
+ will be suspended and resumed synchronously.
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