[PATCH v4] Documentation/ABI: update cpuidle sysfs documentation

* [PATCH v4] Documentation/ABI: update cpuidle sysfs documentation
@ 2018-02-06 19:19 Aishwarya Pant
  2018-02-07 10:36 ` Rafael J. Wysocki
  0 siblings, 1 reply; 2+ messages in thread
From: Aishwarya Pant @ 2018-02-06 19:19 UTC (permalink / raw)
  To: Rafael J. Wysocki, Daniel Lezcano, linux-pm, linux-kernel,
	Jonathan Corbet, Greg KH
  Cc: Julia Lawall

Update cpuidle documentation using git logs and existing documentation
in Documentation/cpuidle/sysfs.txt. This might be useful for scripting
and tracking changes in the ABI.

Signed-off-by: Aishwarya Pant <aishpant@gmail.com>
---
Changes in v4:
- Fix patch formatting
v3:
- Fix subject line
v2:
- Merge cpuidle_sysfs_switch attributes' description with the previous
  entry.

 Documentation/ABI/testing/sysfs-devices-system-cpu | 77 +++++++++++++++++++++-
 1 file changed, 75 insertions(+), 2 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index bfd29bc8d37a..e9ee67f80933 100644
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -108,6 +108,8 @@ Description:	CPU topology files that describe a logical CPU's relationship
 
 What:		/sys/devices/system/cpu/cpuidle/current_driver
 		/sys/devices/system/cpu/cpuidle/current_governer_ro
+		/sys/devices/system/cpu/cpuidle/available_governors
+		/sys/devices/system/cpu/cpuidle/current_governor
 Date:		September 2007
 Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
 Description:	Discover cpuidle policy and mechanism
@@ -119,13 +121,84 @@ Description:	Discover cpuidle policy and mechanism
 		Idle policy (governor) is differentiated from idle mechanism
 		(driver)
 
-		current_driver: displays current idle mechanism
+		current_driver: (RO) displays current idle mechanism
 
-		current_governor_ro: displays current idle policy
+		current_governor_ro: (RO) displays current idle policy
+
+		With the cpuidle_sysfs_switch boot option enabled (meant for
+		developer testing), the following three attributes are visible
+		instead:
+
+		current_driver: same as described above
+
+		available_governors: (RO) displays a space separated list of
+		available governors
+
+		current_governor: (RW) displays current idle policy. Users can
+		switch the governor at runtime by writing to this file.
 
 		See files in Documentation/cpuidle/ for more information.
 
 
+What:		/sys/devices/system/cpu/cpuX/cpuidle/stateN/name
+		/sys/devices/system/cpu/cpuX/cpuidle/stateN/latency
+		/sys/devices/system/cpu/cpuX/cpuidle/stateN/power
+		/sys/devices/system/cpu/cpuX/cpuidle/stateN/time
+		/sys/devices/system/cpu/cpuX/cpuidle/stateN/usage
+Date:		September 2007
+KernelVersion:	v2.6.24
+Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
+Description:
+		The directory /sys/devices/system/cpu/cpuX/cpuidle contains per
+		logical CPU specific cpuidle information for each online cpu X.
+		The processor idle states which are available for use have the
+		following attributes:
+
+		name: (RO) Name of the idle state (string).
+
+		latency: (RO) The latency to exit out of this idle state (in
+		microseconds).
+
+		power: (RO) The power consumed while in this idle state (in
+		milliwatts).
+
+		time: (RO) The total time spent in this idle state (in microseconds).
+
+		usage: (RO) Number of times this state was entered (a count).
+
+
+What:		/sys/devices/system/cpu/cpuX/cpuidle/stateN/desc
+Date:		February 2008
+KernelVersion:	v2.6.25
+Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
+Description:
+		(RO) A small description about the idle state (string).
+
+
+What:		/sys/devices/system/cpu/cpuX/cpuidle/stateN/disable
+Date:		March 2012
+KernelVersion:	v3.10
+Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
+Description:
+		(RW) Option to disable this idle state (bool). The behavior and
+		the effect of the disable variable depends on the implementation
+		of a particular governor. In the ladder governor, for example,
+		it is not coherent, i.e. if one is disabling a light state, then
+		all deeper states are disabled as well, but the disable variable
+		does not reflect it. Likewise, if one enables a deep state but a
+		lighter state still is disabled, then this has no effect.
+
+
+What:		/sys/devices/system/cpu/cpuX/cpuidle/stateN/residency
+Date:		March 2014
+KernelVersion:	v3.15
+Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
+Description:
+		(RO) Display the target residency i.e. the minimum amount of
+		time (in microseconds) this cpu should spend in this idle state
+		to make the transition worth the effort.
+
+
 What:		/sys/devices/system/cpu/cpu#/cpufreq/*
 Date:		pre-git history
 Contact:	linux-pm@vger.kernel.org
-- 
2.16.1

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