This enables the /sys/devices/.../power/runtime_status attribute to
allow the user space to get notifications via poll/select when the device
runtime PM status is changed.
An example use case is to avoid unnecessary accesses for device statistics
(e.g. diskstats for block devices) while the device is in runtime suspend
by user space LED device actitity trigger.
Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Cc: Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
Signed-off-by: Akinobu Mita <akinobu.mita@xxxxxxxxx>
---
Documentation/ABI/testing/sysfs-devices-power | 2 ++
drivers/base/power/power.h | 1 +
drivers/base/power/runtime.c | 1 +
drivers/base/power/sysfs.c | 5 +++++
4 files changed, 9 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-devices-power b/Documentation/ABI/testing/sysfs-devices-power
index 3e50536..47dc357 100644
--- a/Documentation/ABI/testing/sysfs-devices-power
+++ b/Documentation/ABI/testing/sysfs-devices-power
@@ -269,3 +269,5 @@ Description:
the current runtime PM status of the device, which may be
"suspended", "suspending", "resuming", "active", "error" (fatal
error), or "unsupported" (runtime PM is disabled).
+ This attribute allows the user space to get notifications via
+ poll/select when the device runtime PM status is changed.
diff --git a/drivers/base/power/power.h b/drivers/base/power/power.h
index ec33fbdb..8891bf4 100644
--- a/drivers/base/power/power.h
+++ b/drivers/base/power/power.h
@@ -74,6 +74,7 @@ extern int pm_qos_sysfs_add_flags(struct device *dev);
extern void pm_qos_sysfs_remove_flags(struct device *dev);
extern int pm_qos_sysfs_add_latency_tolerance(struct device *dev);
extern void pm_qos_sysfs_remove_latency_tolerance(struct device *dev);
+extern void sysfs_notify_runtime_status(struct device *dev);
#else /* CONFIG_PM */
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index b753355..3a3e413 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -94,6 +94,7 @@ static void __update_runtime_status(struct device *dev, enum rpm_status status)
{
update_pm_runtime_accounting(dev);
dev->power.runtime_status = status;
+ sysfs_notify_runtime_status(dev);
}
static u64 rpm_get_accounted_time(struct device *dev, bool suspended)
diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c
index 1b9c281c..e86d8cb 100644
--- a/drivers/base/power/sysfs.c
+++ b/drivers/base/power/sysfs.c
@@ -734,3 +734,8 @@ void dpm_sysfs_remove(struct device *dev)
sysfs_unmerge_group(&dev->kobj, &pm_wakeup_attr_group);
sysfs_remove_group(&dev->kobj, &pm_attr_group);
}
+
+void sysfs_notify_runtime_status(struct device *dev)
+{
+ sysfs_notify(&dev->kobj, "power", "runtime_status");
+}
--
2.7.4
