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authorDavid Brownell <david-b@pacbell.net>2008-01-10 19:26:57 -0500
committerLen Brown <len.brown@intel.com>2008-02-01 18:30:59 -0500
commitffffa4b502099a03b5215b814fdcd79fb4348854 (patch)
tree31fd59aaca4278f0c124e77d427dbc58d98a2bf4 /Documentation/power
parent5a0a2f304612bd63948177fef05987f4bcaddcaf (diff)
PM: Remove obsolete /sys/devices/.../power/state docs
The /sys/devices/.../power/state files have been gone for a while now, but I just noticed some documentation that still refers to them. (Fortunately described as DEPRECATED and WILL REMOVE). Time to remove that obsolete documentation too ... Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Acked-by: Pavel Machek <pavel@ucw.cz> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Signed-off-by: Len Brown <len.brown@intel.com>
Diffstat (limited to 'Documentation/power')
-rw-r--r--Documentation/power/devices.txt49
1 files changed, 0 insertions, 49 deletions
diff --git a/Documentation/power/devices.txt b/Documentation/power/devices.txt
index d0e79d5820a5..c53d26361919 100644
--- a/Documentation/power/devices.txt
+++ b/Documentation/power/devices.txt
@@ -502,52 +502,3 @@ If the CPU can have a "cpufreq" driver, there also may be opportunities
502to shift to lower voltage settings and reduce the power cost of executing 502to shift to lower voltage settings and reduce the power cost of executing
503a given number of instructions. (Without voltage adjustment, it's rare 503a given number of instructions. (Without voltage adjustment, it's rare
504for cpufreq to save much power; the cost-per-instruction must go down.) 504for cpufreq to save much power; the cost-per-instruction must go down.)
505
506
507/sys/devices/.../power/state files
508==================================
509For now you can also test some of this functionality using sysfs.
510
511 DEPRECATED: USE "power/state" ONLY FOR DRIVER TESTING, AND
512 AVOID USING dev->power.power_state IN DRIVERS.
513
514 THESE WILL BE REMOVED. IF THE "power/state" FILE GETS REPLACED,
515 IT WILL BECOME SOMETHING COUPLED TO THE BUS OR DRIVER.
516
517In each device's directory, there is a 'power' directory, which contains
518at least a 'state' file. The value of this field is effectively boolean,
519PM_EVENT_ON or PM_EVENT_SUSPEND.
520
521 * Reading from this file displays a value corresponding to
522 the power.power_state.event field. All nonzero values are
523 displayed as "2", corresponding to a low power state; zero
524 is displayed as "0", corresponding to normal operation.
525
526 * Writing to this file initiates a transition using the
527 specified event code number; only '0', '2', and '3' are
528 accepted (without a newline); '2' and '3' are both
529 mapped to PM_EVENT_SUSPEND.
530
531On writes, the PM core relies on that recorded event code and the device/bus
532capabilities to determine whether it uses a partial suspend() or resume()
533sequence to change things so that the recorded event corresponds to the
534numeric parameter.
535
536 - If the bus requires the irqs-disabled suspend_late()/resume_early()
537 phases, writes fail because those operations are not supported here.
538
539 - If the recorded value is the expected value, nothing is done.
540
541 - If the recorded value is nonzero, the device is partially resumed,
542 using the bus.resume() and/or class.resume() methods.
543
544 - If the target value is nonzero, the device is partially suspended,
545 using the class.suspend() and/or bus.suspend() methods and the
546 PM_EVENT_SUSPEND message.
547
548Drivers have no way to tell whether their suspend() and resume() calls
549have come through the sysfs power/state file or as part of entering a
550system sleep state, except that when accessed through sysfs the normal
551parent/child sequencing rules are ignored. Drivers (such as bus, bridge,
552or hub drivers) which expose child devices may need to enforce those rules
553on their own.