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author | Linus Torvalds <torvalds@linux-foundation.org> | 2020-02-07 23:49:10 +0300 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-02-07 23:49:10 +0300 |
commit | ba7dcfc7badad87e450e4aaec79662a038dbf9ed (patch) | |
tree | 6941e036ee5d5dddcf033789c5f672b596f0e8cd /Documentation/power/interface.rst | |
parent | c16b99d6c5a3f103ae45e33084055a2440d70544 (diff) | |
parent | 332008256f1f7cd8294acd6e288fb821f685d1a9 (diff) | |
download | linux-ba7dcfc7badad87e450e4aaec79662a038dbf9ed.tar.xz |
Merge tag 'pm-5.6-rc1-3' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull more power management updates from Rafael Wysocki:
- Update the recently merged CPR (Core Power Reduction) support in the
AVS (Adaptive Voltage Scaling) subsystem (Brendan Higgins, Nathan
Chancellor, Niklas Cassel)
- Update the rockchip-io AVS driver (Heiko Stuebner)
- Add two more module parameters to intel_idle on top of the recently
merged material (Rafael Wysocki)
- Clean up a piece of cpuidle documentation and consolidate system
sleep states documentation (Rafael Wysocki)
* tag 'pm-5.6-rc1-3' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
cpuidle: Documentation: Clean up PM QoS description
Documentation: admin-guide: PM: Update sleep states documentation
intel_idle: Introduce 'states_off' module parameter
intel_idle: Introduce 'use_acpi' module parameter
power: avs: qcom-cpr: Avoid clang -Wsometimes-uninitialized in cpr_scale
power: avs: qcom-cpr: add unspecified HAS_IOMEM dependency
PM / AVS: rockchip-io: fix the supply naming for the emmc supply on px30
power: avs: qcom-cpr: add a printout after the driver has been initialized
Diffstat (limited to 'Documentation/power/interface.rst')
-rw-r--r-- | Documentation/power/interface.rst | 79 |
1 files changed, 0 insertions, 79 deletions
diff --git a/Documentation/power/interface.rst b/Documentation/power/interface.rst deleted file mode 100644 index 8d270ed27228..000000000000 --- a/Documentation/power/interface.rst +++ /dev/null @@ -1,79 +0,0 @@ -=========================================== -Power Management Interface for System Sleep -=========================================== - -Copyright (c) 2016 Intel Corp., Rafael J. Wysocki <rafael.j.wysocki@intel.com> - -The power management subsystem provides userspace with a unified sysfs interface -for system sleep regardless of the underlying system architecture or platform. -The interface is located in the /sys/power/ directory (assuming that sysfs is -mounted at /sys). - -/sys/power/state is the system sleep state control file. - -Reading from it returns a list of supported sleep states, encoded as: - -- 'freeze' (Suspend-to-Idle) -- 'standby' (Power-On Suspend) -- 'mem' (Suspend-to-RAM) -- 'disk' (Suspend-to-Disk) - -Suspend-to-Idle is always supported. Suspend-to-Disk is always supported -too as long the kernel has been configured to support hibernation at all -(ie. CONFIG_HIBERNATION is set in the kernel configuration file). Support -for Suspend-to-RAM and Power-On Suspend depends on the capabilities of the -platform. - -If one of the strings listed in /sys/power/state is written to it, the system -will attempt to transition into the corresponding sleep state. Refer to -Documentation/admin-guide/pm/sleep-states.rst for a description of each of -those states. - -/sys/power/disk controls the operating mode of hibernation (Suspend-to-Disk). -Specifically, it tells the kernel what to do after creating a hibernation image. - -Reading from it returns a list of supported options encoded as: - -- 'platform' (put the system into sleep using a platform-provided method) -- 'shutdown' (shut the system down) -- 'reboot' (reboot the system) -- 'suspend' (trigger a Suspend-to-RAM transition) -- 'test_resume' (resume-after-hibernation test mode) - -The currently selected option is printed in square brackets. - -The 'platform' option is only available if the platform provides a special -mechanism to put the system to sleep after creating a hibernation image (ACPI -does that, for example). The 'suspend' option is available if Suspend-to-RAM -is supported. Refer to Documentation/power/basic-pm-debugging.rst for the -description of the 'test_resume' option. - -To select an option, write the string representing it to /sys/power/disk. - -/sys/power/image_size controls the size of hibernation images. - -It can be written a string representing a non-negative integer that will be -used as a best-effort upper limit of the image size, in bytes. The hibernation -core will do its best to ensure that the image size will not exceed that number. -However, if that turns out to be impossible to achieve, a hibernation image will -still be created and its size will be as small as possible. In particular, -writing '0' to this file will enforce hibernation images to be as small as -possible. - -Reading from this file returns the current image size limit, which is set to -around 2/5 of available RAM by default. - -/sys/power/pm_trace controls the PM trace mechanism saving the last suspend -or resume event point in the RTC across reboots. - -It helps to debug hard lockups or reboots due to device driver failures that -occur during system suspend or resume (which is more common) more effectively. - -If /sys/power/pm_trace contains '1', the fingerprint of each suspend/resume -event point in turn will be stored in the RTC memory (overwriting the actual -RTC information), so it will survive a system crash if one occurs right after -storing it and it can be used later to identify the driver that caused the crash -to happen (see Documentation/power/s2ram.rst for more information). - -Initially it contains '0' which may be changed to '1' by writing a string -representing a nonzero integer into it. |