summaryrefslogtreecommitdiff
path: root/Documentation/power/states.txt
diff options
context:
space:
mode:
authorTakashi Iwai <tiwai@suse.de>2013-06-05 15:21:29 +0200
committerTakashi Iwai <tiwai@suse.de>2013-06-05 15:21:29 +0200
commitc9e34d1525ffd554f29dc01674eac279de2e759d (patch)
tree577ff9e4a92e5ebaca1196d7e60b0963eac427fc /Documentation/power/states.txt
parent02b504d9d8e565081b99176e7e464821d76fc994 (diff)
parent11e7064f35bb87da8f427d1aa4bbd8b7473a3993 (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.txt30
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.