Lines Matching +full:power +full:- +full:on
1 .. SPDX-License-Identifier: GPL-2.0
13 Sleep states are global low-power states of the entire system in which user
21 Depending on its configuration and the capabilities of the platform it runs on,
28 Suspend-to-Idle
29 ---------------
31 This is a generic, pure software, light-weight variant of system suspend (also
34 I/O devices into low-power states (possibly lower-power than available in the
38 The system is woken up from this state by in-band interrupts, so theoretically
42 This state can be used on platforms without support for :ref:`standby <standby>`
43 or :ref:`suspend-to-RAM <s2ram>`, or it can be used in addition to any of the
50 -------
54 operating state is lost (the system core logic retains power), so the system can
58 I/O devices into low-power states, which is done for :ref:`suspend-to-idle
59 <s2idle>` too, nonboot CPUs are taken offline and all low-level system functions
61 allow more energy to be saved relative to :ref:`suspend-to-idle <s2idle>`, but
65 reduced relative to :ref:`suspend-to-idle <s2idle>` and it may be necessary to
66 rely on the platform for setting up the wakeup functionality as appropriate.
70 core system suspend subsystem. On ACPI-based systems this state is mapped to
75 Suspend-to-RAM
76 --------------
79 energy savings as everything in the system is put into a low-power state, except
80 for memory, which should be placed into the self-refresh mode to retain its
83 take place depending on the platform capabilities. In particular, on ACPI-based
86 more low-level components that are not directly controlled by the kernel.
89 suspended and put into low-power states. In many cases, all peripheral buses
90 lose power when entering S2RAM, so devices must be able to handle the transition
91 back to the "on" state.
93 On ACPI-based systems S2RAM requires some minimal boot-strapping code in the
94 platform firmware to resume the system from it. This may be the case on other
98 relative to :ref:`suspend-to-idle <s2idle>` and :ref:`standby <standby>` and it
99 may be necessary to rely on the platform for setting up the wakeup functionality
104 suspend subsystem. On ACPI-based systems it is mapped to the S3 system state
110 -----------
112 This state (also referred to as Suspend-to-Disk or STD) offers the greatest
113 energy savings and can be used even in the absence of low-level platform support
114 for system suspend. However, it requires some low-level code for resuming the
124 is written out and finally the system goes into the target low-power state in
125 which power is cut from almost all of its hardware components, including memory,
129 special low-power state (like ACPI S4), or it may simply power down itself.
130 Powering down means minimum power draw and it allows this mechanism to work on
131 any system. However, entering a special low-power state may allow additional
132 means of system wakeup to be used (e.g. pressing a key on the keyboard or
137 the boot loader, depending on the system configuration, but anyway it causes
144 the special architecture-specific low-level code is needed. Finally, the
145 image kernel restores the system to the pre-hibernation state and allows user
150 for the given CPU architecture includes the low-level code for system resume.
156 The power management subsystem provides userspace with a unified ``sysfs``
158 platform. That interface is located in the :file:`/sys/power/` directory
169 :ref:`hibernation <hibernation>`, :ref:`suspend-to-idle <s2idle>` and
183 and "deep". The "s2idle" string always represents :ref:`suspend-to-idle
185 :ref:`standby <standby>` and :ref:`suspend-to-RAM <s2ram>`,
197 This file controls the operating mode of hibernation (Suspend-to-Disk).
204 Put the system into a special low-power state (e.g. ACPI S4) to
215 Power off the system.
241 to :file:`/sys/power/state`.
248 It can be written a string representing a non-negative integer that will
249 be used as a best-effort upper limit of the image size, in bytes. The
275 :ref:`suspend-to-idle <s2idle>` state. The first one is to write "freeze"
276 directly to :file:`/sys/power/state`. The second one is to write "s2idle" to
277 :file:`/sys/power/mem_sleep` and then to write "mem" to
278 :file:`/sys/power/state`. Likewise, there are two ways to make the system go
282 system go into the :ref:`suspend-to-RAM <s2ram>` state (write "deep" into
283 :file:`/sys/power/mem_sleep` and "mem" into :file:`/sys/power/state`).
286 into :file:`/sys/power/mem_sleep`) is either "deep" (on the majority of systems
287 supporting :ref:`suspend-to-RAM <s2ram>`) or "s2idle", but it can be overridden
289 On some systems with ACPI, depending on the information in the ACPI tables, the
290 default may be "s2idle" even if :ref:`suspend-to-RAM <s2ram>` is supported in