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PM: Remove obsolete /sys/devices/.../power/state docs

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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>
This commit is contained in:
David Brownell 2008-01-11 01:26:57 +01:00 committed by Len Brown
parent 5a0a2f3046
commit ffffa4b502
1 changed files with 0 additions and 49 deletions
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49
Documentation/power/devices.txt
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@ -502,52 +502,3 @@ If the CPU can have a "cpufreq" driver, there also may be opportunities
to shift to lower voltage settings and reduce the power cost of executing to shift to lower voltage settings and reduce the power cost of executing
a given number of instructions. (Without voltage adjustment, it's rare a given number of instructions. (Without voltage adjustment, it's rare
for cpufreq to save much power; the cost-per-instruction must go down.) for cpufreq to save much power; the cost-per-instruction must go down.)
/sys/devices/.../power/state files
==================================
For now you can also test some of this functionality using sysfs.
DEPRECATED: USE "power/state" ONLY FOR DRIVER TESTING, AND
AVOID USING dev->power.power_state IN DRIVERS.
THESE WILL BE REMOVED. IF THE "power/state" FILE GETS REPLACED,
IT WILL BECOME SOMETHING COUPLED TO THE BUS OR DRIVER.
In each device's directory, there is a 'power' directory, which contains
at least a 'state' file. The value of this field is effectively boolean,
PM_EVENT_ON or PM_EVENT_SUSPEND.
* Reading from this file displays a value corresponding to
the power.power_state.event field. All nonzero values are
displayed as "2", corresponding to a low power state; zero
is displayed as "0", corresponding to normal operation.
* Writing to this file initiates a transition using the
specified event code number; only '0', '2', and '3' are
accepted (without a newline); '2' and '3' are both
mapped to PM_EVENT_SUSPEND.
On writes, the PM core relies on that recorded event code and the device/bus
capabilities to determine whether it uses a partial suspend() or resume()
sequence to change things so that the recorded event corresponds to the
numeric parameter.
- If the bus requires the irqs-disabled suspend_late()/resume_early()
phases, writes fail because those operations are not supported here.
- If the recorded value is the expected value, nothing is done.
- If the recorded value is nonzero, the device is partially resumed,
using the bus.resume() and/or class.resume() methods.
- If the target value is nonzero, the device is partially suspended,
using the class.suspend() and/or bus.suspend() methods and the
PM_EVENT_SUSPEND message.
Drivers have no way to tell whether their suspend() and resume() calls
have come through the sysfs power/state file or as part of entering a
system sleep state, except that when accessed through sysfs the normal
parent/child sequencing rules are ignored. Drivers (such as bus, bridge,
or hub drivers) which expose child devices may need to enforce those rules
on their own.