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SubjectRe: [PATCH 2/3,v2] acpi: thermal/sysfs-api.txt: document passive attribute for thermal zones
Signed-off-by: Frans Pop <>
Cc: Zhang Rui <>
Cc: Sujith Thomas <>

While working on some further patches I discovered that polling_delay does
not actually determine the polling interval for a forced passive trip
point. Instead a hardcoded interval of 1 second is used (passive_delay).

I also saw that the thermal_sys driver is somewhat independent of ACPI,
so the third patch in the series may not be appropriate.

diff --git a/Documentation/thermal/sysfs-api.txt b/Documentation/thermal/sysfs-api.txt
index 48e9c5c..f6b3743 100644
--- a/Documentation/thermal/sysfs-api.txt
+++ b/Documentation/thermal/sysfs-api.txt
@@ -3,7 +3,7 @@ Generic Thermal Sysfs driver How To

Written by Sujith Thomas <>, Zhang Rui <>

-Updated: 2 January 2008
+Updated: 21 August 2009

Copyright (c) 2008 Intel Corporation

@@ -199,6 +199,15 @@ cdev[0-*]_trip_point
RO, Optional

+ Attribute is only present for zones which do not have a passive
+ cooling policy (_PSV) defined in ACPI. Default is zero and can be
+ set to a temperature (in millidegrees) to enable a passive trip
+ point for the zone. Activation is done by polling with an interval
+ of 1 second.
+ Unit: millidegrees Celsius
+ RW, Optional
* Cooling device attributes *
@@ -230,8 +239,9 @@ thermal_zone_device (thermal_zone1) with 4 trip points in all.
It has one processor and one fan, which are both registered as

-If the processor is listed in _PSL method, and the fan is listed in _AL0
-method, the sys I/F structure will be built like this:
+If the processor is listed in _PSL method, the fan is listed in _AL0
+method, and the zone has a _PSV method, the sys I/F structure will be
+built like this:


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