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authorLinus Torvalds <torvalds@linux-foundation.org>2009-09-23 09:32:11 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-09-23 09:32:11 -0700
commitc11f6c82581e8be4e1829c677db54e7f55cebece (patch)
tree1a116241b0831ded998aabe800bdc24104cbd826 /Documentation/hwmon
parent40aba218969914d1b225e742617adb921cf94eae (diff)
parent193a6dec1c0246a80b6d0101e4f351ccf877bcac (diff)
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Merge branch 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6
* 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6: (119 commits) ACPI: don't pass handle for fixed hardware notifications ACPI: remove null pointer checks in deferred execution path ACPI: simplify deferred execution path acerhdf: additional BIOS versions acerhdf: convert to dev_pm_ops acerhdf: fix fan control for AOA150 model thermal: add missing Kconfig dependency acpi: switch /proc/acpi/{debug_layer,debug_level} to seq_file hp-wmi: fix rfkill memory leak on unload ACPI: remove unnecessary #ifdef CONFIG_DMI ACPI: linux/acpi.h should not include linux/dmi.h hwmon driver for ACPI 4.0 power meters topstar-laptop: add new driver for hotkeys support on Topstar N01 thinkpad_acpi: fix rfkill memory leak on unload thinkpad-acpi: report brightness events when required thinkpad-acpi: don't poll by default any of the reserved hotkeys thinkpad-acpi: Fix procfs hotkey reset command thinkpad-acpi: deprecate hotkey_bios_mask thinkpad-acpi: hotkey poll fixes thinkpad-acpi: be more strict when detecting a ThinkPad ...
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diff --git a/Documentation/hwmon/acpi_power_meter b/Documentation/hwmon/acpi_power_meter
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+Kernel driver power_meter
+=========================
+
+This driver talks to ACPI 4.0 power meters.
+
+Supported systems:
+ * Any recent system with ACPI 4.0.
+ Prefix: 'power_meter'
+ Datasheet: http://acpi.info/, section 10.4.
+
+Author: Darrick J. Wong
+
+Description
+-----------
+
+This driver implements sensor reading support for the power meters exposed in
+the ACPI 4.0 spec (Chapter 10.4). These devices have a simple set of
+features--a power meter that returns average power use over a configurable
+interval, an optional capping mechanism, and a couple of trip points. The
+sysfs interface conforms with the specification outlined in the "Power" section
+of Documentation/hwmon/sysfs-interface.
+
+Special Features
+----------------
+
+The power[1-*]_is_battery knob indicates if the power supply is a battery.
+Both power[1-*]_average_{min,max} must be set before the trip points will work.
+When both of them are set, an ACPI event will be broadcast on the ACPI netlink
+socket and a poll notification will be sent to the appropriate
+power[1-*]_average sysfs file.
+
+The power[1-*]_{model_number, serial_number, oem_info} fields display arbitrary
+strings that ACPI provides with the meter. The measures/ directory contains
+symlinks to the devices that this meter measures.
+
+Some computers have the ability to enforce a power cap in hardware. If this is
+the case, the power[1-*]_cap and related sysfs files will appear. When the
+average power consumption exceeds the cap, an ACPI event will be broadcast on
+the netlink event socket and a poll notification will be sent to the
+appropriate power[1-*]_alarm file to indicate that capping has begun, and the
+hardware has taken action to reduce power consumption. Most likely this will
+result in reduced performance.
+
+There are a few other ACPI notifications that can be sent by the firmware. In
+all cases the ACPI event will be broadcast on the ACPI netlink event socket as
+well as sent as a poll notification to a sysfs file. The events are as
+follows:
+
+power[1-*]_cap will be notified if the firmware changes the power cap.
+power[1-*]_interval will be notified if the firmware changes the averaging
+interval.
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