Merge branch 'pm-sleep' (ee7f9d7c) · Commits · 戴 / test

Documentation/ABI/testing/sysfs-power

+20 −9

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		@@ -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

Documentation/kernel-parameters.txt

+7 −0

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		@@ -2889,6 +2889,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
		[KNL, SMP] Set scheduler's default relax_domain_level.
		See Documentation/cgroups/cpusets.txt.

		relative_sleep_states=
		[SUSPEND] Use sleep state labeling where the deepest
		state available other than hibernation is always "mem".
		Format: { "0" \| "1" }
		0 -- Traditional sleep state labels.
		1 -- Relative sleep state labels.

		reserve= [KNL,BUGS] Force the kernel to ignore some iomem area

		reservetop= [X86-32]

Documentation/power/devices.txt

+30 −4

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		@@ -2,6 +2,7 @@ Device Power Management

		Copyright (c) 2010-2011 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
		Copyright (c) 2010 Alan Stern <stern@rowland.harvard.edu>
		Copyright (c) 2014 Intel Corp., Rafael J. Wysocki <rafael.j.wysocki@intel.com>


		Most of the code in Linux is device drivers, so most of the Linux power
		@@ -326,6 +327,20 @@ the phases are:
		driver in some way for the upcoming system power transition, but it
		should not put the device into a low-power state.

		For devices supporting runtime power management, the return value of the
		prepare callback can be used to indicate to the PM core that it may
		safely leave the device in runtime suspend (if runtime-suspended
		already), provided that all of the device's descendants are also left in
		runtime suspend. Namely, if the prepare callback returns a positive
		number and that happens for all of the descendants of the device too,
		and all of them (including the device itself) are runtime-suspended, the
		PM core will skip the suspend, suspend_late and suspend_noirq suspend
		phases as well as the resume_noirq, resume_early and resume phases of
		the following system resume for all of these devices. In that case,
		the complete callback will be called directly after the prepare callback
		and is entirely responsible for bringing the device back to the
		functional state as appropriate.

		2. The suspend methods should quiesce the device to stop it from performing
		I/O. They also may save the device registers and put it into the
		appropriate low-power state, depending on the bus type the device is on,
		@@ -400,12 +415,23 @@ When resuming from freeze, standby or memory sleep, the phases are:
		the resume callbacks occur; it's not necessary to wait until the
		complete phase.

		Moreover, if the preceding prepare callback returned a positive number,
		the device may have been left in runtime suspend throughout the whole
		system suspend and resume (the suspend, suspend_late, suspend_noirq
		phases of system suspend and the resume_noirq, resume_early, resume
		phases of system resume may have been skipped for it). In that case,
		the complete callback is entirely responsible for bringing the device
		back to the functional state after system suspend if necessary. [For
		example, it may need to queue up a runtime resume request for the device
		for this purpose.] To check if that is the case, the complete callback
		can consult the device's power.direct_complete flag. Namely, if that
		flag is set when the complete callback is being run, it has been called
		directly after the preceding prepare and special action may be required
		to make the device work correctly afterward.

		At the end of these phases, drivers should be as functional as they were before
		suspending: I/O can be performed using DMA and IRQs, and the relevant clocks are
		gated on. Even if the device was in a low-power state before the system sleep
		because of runtime power management, afterwards it should be back in its
		full-power state. There are multiple reasons why it's best to do this; they are
		discussed in more detail in Documentation/power/runtime_pm.txt.
		gated on.

		However, the details here may again be platform-specific. For example,
		some systems support multiple "run" states, and the mode in effect at

Documentation/power/runtime_pm.txt

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		@@ -2,6 +2,7 @@ Runtime Power Management Framework for I/O Devices

		(C) 2009-2011 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
		(C) 2010 Alan Stern <stern@rowland.harvard.edu>
		(C) 2014 Intel Corp., Rafael J. Wysocki <rafael.j.wysocki@intel.com>

		1. Introduction

		@@ -444,6 +445,10 @@ drivers/base/power/runtime.c and include/linux/pm_runtime.h:
		bool pm_runtime_status_suspended(struct device *dev);
		- return true if the device's runtime PM status is 'suspended'

		bool pm_runtime_suspended_if_enabled(struct device *dev);
		- return true if the device's runtime PM status is 'suspended' and its
		'power.disable_depth' field is equal to 1

		void pm_runtime_allow(struct device *dev);
		- set the power.runtime_auto flag for the device and decrease its usage
		counter (used by the /sys/devices/.../power/control interface to
		@@ -644,6 +649,18 @@ place (in particular, if the system is not waking up from hibernation), it may
		be more efficient to leave the devices that had been suspended before the system
		suspend began in the suspended state.

		To this end, the PM core provides a mechanism allowing some coordination between
		different levels of device hierarchy. Namely, if a system suspend .prepare()
		callback returns a positive number for a device, that indicates to the PM core
		that the device appears to be runtime-suspended and its state is fine, so it
		may be left in runtime suspend provided that all of its descendants are also
		left in runtime suspend. If that happens, the PM core will not execute any
		system suspend and resume callbacks for all of those devices, except for the
		complete callback, which is then entirely responsible for handling the device
		as appropriate. This only applies to system suspend transitions that are not
		related to hibernation (see Documentation/power/devices.txt for more
		information).

		The PM core does its best to reduce the probability of race conditions between
		the runtime PM and system suspend/resume (and hibernation) callbacks by carrying
		out the following operations:

Documentation/power/states.txt

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		System Power Management Sleep States

		System Power Management States
		(C) 2014 Intel Corp., Rafael J. Wysocki <rafael.j.wysocki@intel.com>

		The kernel supports up to four system sleep states generically, although three
		of them depend on the platform support code to implement the low-level details
		for each state.

		The kernel supports four power management states generically, though
		one is generic and the other three are dependent on platform support
		code to implement the low-level details for each state.
		This file describes each state, what they are
		commonly called, what ACPI state they map to, and what string to write
		to /sys/power/state to enter that state
		The states are represented by strings that can be read or written to the
		/sys/power/state file. Those strings may be "mem", "standby", "freeze" and
		"disk", where the last one always represents hibernation (Suspend-To-Disk) and
		the meaning of the remaining ones depends on the relative_sleep_states command
		line argument.

		state: Freeze / Low-Power Idle
		For relative_sleep_states=1, the strings "mem", "standby" and "freeze" label the
		available non-hibernation sleep states from the deepest to the shallowest,
		respectively. In that case, "mem" is always present in /sys/power/state,
		because there is at least one non-hibernation sleep state in every system. If
		the given system supports two non-hibernation sleep states, "standby" is present
		in /sys/power/state in addition to "mem". If the system supports three
		non-hibernation sleep states, "freeze" will be present in /sys/power/state in
		addition to "mem" and "standby".

		For relative_sleep_states=0, which is the default, the following descriptions
		apply.

		state: Suspend-To-Idle
		ACPI state: S0
		String: "freeze"
		Label: "freeze"

		This state is a generic, pure software, light-weight, low-power state.
		It allows more energy to be saved relative to idle by freezing user
		This state is a generic, pure software, light-weight, system sleep state.
		It allows more energy to be saved relative to runtime idle by freezing user
		space and putting all I/O devices into low-power states (possibly
		lower-power than available at run time), such that the processors can
		spend more time in their idle states.
		This state can be used for platforms without Standby/Suspend-to-RAM

		This state can be used for platforms without Power-On Suspend/Suspend-to-RAM
		support, or it can be used in addition to Suspend-to-RAM (memory sleep)
		to provide reduced resume latency.
		to provide reduced resume latency. It is always supported.


		State: Standby / Power-On Suspend
		ACPI State: S1
		String: "standby"
		Label: "standby"

		This state offers minimal, though real, power savings, while providing
		a very low-latency transition back to a working system. No operating
		state is lost (the CPU retains power), so the system easily starts up
		This state, if supported, offers moderate, though real, power savings, while
		providing a relatively low-latency transition back to a working system. No
		operating state is lost (the CPU retains power), so the system easily starts up
		again where it left off.

		We try to put devices in a low-power state equivalent to D1, which
		also offers low power savings, but low resume latency. Not all devices
		support D1, and those that don't are left on.
		In addition to freezing user space and putting all I/O devices into low-power
		states, which is done for Suspend-To-Idle too, nonboot CPUs are taken offline
		and all low-level system functions are suspended during transitions into this
		state. For this reason, it should allow more energy to be saved relative to
		Suspend-To-Idle, but the resume latency will generally be greater than for that
		state.


		State: Suspend-to-RAM
		ACPI State: S3
		String: "mem"
		Label: "mem"

		This state offers significant power savings as everything in the
		system is put into a low-power state, except for memory, which is
		placed in self-refresh mode to retain its contents.
		This state, if supported, offers significant power savings as everything in the
		system is put into a low-power state, except for memory, which should be placed
		into the self-refresh mode to retain its contents. All of the steps carried out
		when entering Power-On Suspend are also carried out during transitions to STR.
		Additional operations may take place depending on the platform capabilities. In
		particular, on ACPI systems the kernel passes control to the BIOS (platform
		firmware) as the last step during STR transitions and that usually results in
		powering down some more low-level components that aren't directly controlled by
		the kernel.

		System and device state is saved and kept in memory. All devices are
		suspended and put into D3. In many cases, all peripheral buses lose
		power when entering STR, so devices must be able to handle the
		transition back to the On state.
		System and device state is saved and kept in memory. All devices are suspended
		and put into low-power states. In many cases, all peripheral buses lose power
		when entering STR, so devices must be able to handle the transition back to the
		"on" state.

		For at least ACPI, STR requires some minimal boot-strapping code to
		resume the system from STR. This may be true on other platforms.
		For at least ACPI, STR requires some minimal boot-strapping code to resume the
		system from it. This may be the case on other platforms too.


		State: Suspend-to-disk
		ACPI State: S4
		String: "disk"
		Label: "disk"

		This state offers the greatest power savings, and can be used even in
		the absence of low-level platform support for power management. This

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