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-rw-r--r--Documentation/ABI/testing/sysfs-power29
1 files changed, 20 insertions, 9 deletions
diff --git a/Documentation/ABI/testing/sysfs-power b/Documentation/ABI/testing/sysfs-power
index 64c9276e9421..f4551816329e 100644
--- a/Documentation/ABI/testing/sysfs-power
+++ b/Documentation/ABI/testing/sysfs-power
@@ -7,19 +7,30 @@ Description:
subsystem.
What: /sys/power/state
-Date: August 2006
+Date: May 2014
Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
Description:
- The /sys/power/state file controls the system power state.
- Reading from this file returns what states are supported,
- which is hard-coded to 'freeze' (Low-Power Idle), 'standby'
- (Power-On Suspend), 'mem' (Suspend-to-RAM), and 'disk'
- (Suspend-to-Disk).
+ The /sys/power/state file controls system sleep states.
+ Reading from this file returns the available sleep state
+ labels, which may be "mem", "standby", "freeze" and "disk"
+ (hibernation). The meanings of the first three labels depend on
+ the relative_sleep_states command line argument as follows:
+ 1) relative_sleep_states = 1
+ "mem", "standby", "freeze" represent non-hibernation sleep
+ states from the deepest ("mem", always present) to the
+ shallowest ("freeze"). "standby" and "freeze" may or may
+ not be present depending on the capabilities of the
+ platform. "freeze" can only be present if "standby" is
+ present.
+ 2) relative_sleep_states = 0 (default)
+ "mem" - "suspend-to-RAM", present if supported.
+ "standby" - "power-on suspend", present if supported.
+ "freeze" - "suspend-to-idle", always present.
Writing to this file one of these strings causes the system to
- transition into that state. Please see the file
- Documentation/power/states.txt for a description of each of
- these states.
+ transition into the corresponding state, if available. See
+ Documentation/power/states.txt for a description of what
+ "suspend-to-RAM", "power-on suspend" and "suspend-to-idle" mean.
What: /sys/power/disk
Date: September 2006
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