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author | Takashi Iwai <tiwai@suse.de> | 2013-06-05 15:21:29 +0200 |
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committer | Takashi Iwai <tiwai@suse.de> | 2013-06-05 15:21:29 +0200 |
commit | c9e34d1525ffd554f29dc01674eac279de2e759d (patch) | |
tree | 577ff9e4a92e5ebaca1196d7e60b0963eac427fc /Documentation/power/states.txt | |
parent | 02b504d9d8e565081b99176e7e464821d76fc994 (diff) | |
parent | 11e7064f35bb87da8f427d1aa4bbd8b7473a3993 (diff) |
Merge branch 'for-linus' into for-next
* for-linus: (778 commits)
ALSA: usb-audio - Fix invalid volume resolution on Logitech HD webcam c270
ALSA: usb-audio - Apply Logitech QuickCam Pro 9000 quirk only to audio iface
ALSA: hda/via - Clean up duplicated codes
ALSA: hda/via - Fix wrongly cleared pins after suspend on VT1802
ALSA: hda - Add keep_eapd_on flag to generic parser
ALSA: hda - Allow setting automute/automic hooks after parsing
ALSA: hda/via - Disable broken dynamic power control
ALSA: usb-audio: fix Roland/Cakewalk UM-3G support
ALSA: hda - Add headset quirk for two Dell machines
ALSA: hda - add dock support for Thinkpad T431s
ALSA: sis7019: fix error return code in sis_chip_create()
ASoC: cs42l52: fix default value for MASTERA_VOL.
ASoC: wm8994: check for array index returned
ASoC: wm8994: Fix reporting of accessory removal on WM8958
ASoC: wm8994: use the correct pointer to get the control value
Linux 3.10-rc3
ipc/sem.c: Fix missing wakeups in do_smart_update_queue()
score: remove redundant kcore_list entries
ASoC: wm5110: Correct DSP4R Mixer control name
ARC: lazy dcache flush broke gdb in non-aliasing configs
...
Diffstat (limited to 'Documentation/power/states.txt')
-rw-r--r-- | Documentation/power/states.txt | 30 |
1 files changed, 17 insertions, 13 deletions
diff --git a/Documentation/power/states.txt b/Documentation/power/states.txt index 4416b28630df..442d43df9b25 100644 --- a/Documentation/power/states.txt +++ b/Documentation/power/states.txt @@ -2,12 +2,26 @@ System Power Management States -The kernel supports three power management states generically, though -each is dependent on platform support code to implement the low-level -details for each state. This file describes each state, what they are +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 +state: Freeze / Low-Power Idle +ACPI state: S0 +String: "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 +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 +support, or it can be used in addition to Suspend-to-RAM (memory sleep) +to provide reduced resume latency. + State: Standby / Power-On Suspend ACPI State: S1 @@ -22,9 +36,6 @@ 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. -A transition from Standby to the On state should take about 1-2 -seconds. - State: Suspend-to-RAM ACPI State: S3 @@ -42,9 +53,6 @@ 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. -A transition from Suspend-to-RAM to the On state should take about -3-5 seconds. - State: Suspend-to-disk ACPI State: S4 @@ -74,7 +82,3 @@ low-power state (like ACPI S4), or it may simply power down. Powering down offers greater savings, and allows this mechanism to work on any system. However, entering a real low-power state allows the user to trigger wake up events (e.g. pressing a key or opening a laptop lid). - -A transition from Suspend-to-Disk to the On state should take about 30 -seconds, though it's typically a bit more with the current -implementation. |