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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2016-11-22 00:45:40 +0300
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2016-11-22 00:45:40 +0300
commit406e79385f3223d82272cf2be86bc95cd000a258 (patch)
treecc7e00f0d3be1fe82e062a9d730163b17aa9769d /Documentation/ABI/testing/sysfs-power
parent62a03defeabd58f74e07ca030d6c21e069d4d88e (diff)
downloadlinux-406e79385f3223d82272cf2be86bc95cd000a258.tar.xz
PM / sleep: System sleep state selection interface rework
There are systems in which the platform doesn't support any special sleep states, so suspend-to-idle (PM_SUSPEND_FREEZE) is the only available system sleep state. However, some user space frameworks only use the "mem" and (sometimes) "standby" sleep state labels, so the users of those systems need to modify user space in order to be able to use system suspend at all and that may be a pain in practice. Commit 0399d4db3edf (PM / sleep: Introduce command line argument for sleep state enumeration) attempted to address this problem by adding a command line argument to change the meaning of the "mem" string in /sys/power/state to make it trigger suspend-to-idle (instead of suspend-to-RAM). However, there also are systems in which the platform does support special sleep states, but suspend-to-idle is the preferred one anyway (it even may save more energy than the platform-provided sleep states in some cases) and the above commit doesn't help in those cases. For this reason, rework the system sleep state selection interface again (but preserve backwards compatibiliby). Namely, add a new sysfs file, /sys/power/mem_sleep, that will control the system suspend mode triggered by writing "mem" to /sys/power/state (in analogy with what /sys/power/disk does for hibernation). Make it select suspend-to-RAM ("deep" sleep) by default (if supported) and fall back to suspend-to-idle ("s2idle") otherwise and add a new command line argument, mem_sleep_default, allowing that default to be overridden if need be. At the same time, drop the relative_sleep_states command line argument that doesn't make sense any more. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Tested-by: Mario Limonciello <mario.limonciello@dell.com>
Diffstat (limited to 'Documentation/ABI/testing/sysfs-power')
-rw-r--r--Documentation/ABI/testing/sysfs-power45
1 files changed, 25 insertions, 20 deletions
diff --git a/Documentation/ABI/testing/sysfs-power b/Documentation/ABI/testing/sysfs-power
index 50b368d490b5..f523e5a3ac33 100644
--- a/Documentation/ABI/testing/sysfs-power
+++ b/Documentation/ABI/testing/sysfs-power
@@ -7,30 +7,35 @@ Description:
subsystem.
What: /sys/power/state
-Date: May 2014
+Date: November 2016
Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
Description:
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 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.
+ labels, which may be "mem" (suspend), "standby" (power-on
+ suspend), "freeze" (suspend-to-idle) and "disk" (hibernation).
+
+ Writing one of the above strings to this file causes the system
+ to transition into the corresponding state, if available.
+
+ See Documentation/power/states.txt for more information.
+
+What: /sys/power/mem_sleep
+Date: November 2016
+Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
+Description:
+ The /sys/power/mem_sleep file controls the operating mode of
+ system suspend. Reading from it returns the available modes
+ as "s2idle" (always present), "shallow" and "deep" (present if
+ supported). The mode that will be used on subsequent attempts
+ to suspend the system (by writing "mem" to the /sys/power/state
+ file described above) is enclosed in square brackets.
+
+ Writing one of the above strings to this file causes the mode
+ represented by it to be used on subsequent attempts to suspend
+ the system.
+
+ See Documentation/power/states.txt for more information.
What: /sys/power/disk
Date: September 2006