path: root/Documentation/ABI
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authorAlan Stern <stern@rowland.harvard.edu>2010-09-25 23:35:21 +0200
committerRafael J. Wysocki <rjw@sisk.pl>2010-10-17 01:57:48 +0200
commit15bcb91d7e607d8a2e060f01f7784a7454668da4 (patch)
tree6d59964cb78ab4b7c93a3c4d06f0dad256b99140 /Documentation/ABI
parent7490e44239e60293bca0c2663229050c36c660c2 (diff)
PM / Runtime: Implement autosuspend support
This patch (as1427) implements the "autosuspend" facility for runtime PM. A few new fields are added to the dev_pm_info structure and several new PM helper functions are defined, for telling the PM core whether or not a device uses autosuspend, for setting the autosuspend delay, and for marking periods of device activity. Drivers that do not want to use autosuspend can continue using the same helper functions as before; their behavior will not change. In addition, drivers supporting autosuspend can also call the old helper functions to get the old behavior. The details are all explained in Documentation/power/runtime_pm.txt and Documentation/ABI/testing/sysfs-devices-power. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Diffstat (limited to 'Documentation/ABI')
1 files changed, 18 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-devices-power b/Documentation/ABI/testing/sysfs-devices-power
index 6bb2dd3c3a7..7628cd1bc36 100644
--- a/Documentation/ABI/testing/sysfs-devices-power
+++ b/Documentation/ABI/testing/sysfs-devices-power
@@ -147,3 +147,21 @@ Description:
milliseconds. This attribute is read-only. If the device is
not enabled to wake up the system from sleep states, this
attribute is empty.
+What: /sys/devices/.../power/autosuspend_delay_ms
+Date: September 2010
+Contact: Alan Stern <stern@rowland.harvard.edu>
+ The /sys/devices/.../power/autosuspend_delay_ms attribute
+ contains the autosuspend delay value (in milliseconds). Some
+ drivers do not want their device to suspend as soon as it
+ becomes idle at run time; they want the device to remain
+ inactive for a certain minimum period of time first. That
+ period is called the autosuspend delay. Negative values will
+ prevent the device from being suspended at run time (similar
+ to writing "on" to the power/control attribute). Values >=
+ 1000 will cause the autosuspend timer expiration to be rounded
+ up to the nearest second.
+ Not all drivers support this attribute. If it isn't supported,
+ attempts to read or write it will yield I/O errors.