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Subject[PATCH 8/8] cpuidle: first round of documentation updates


Documentation changes based on Pavel's feedback.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>

Index: linux-2.6.22-rc-mm/Documentation/cpuidle/sysfs.txt
===================================================================
--- linux-2.6.22-rc-mm.orig/Documentation/cpuidle/sysfs.txt 2007-06-06 11:33:25.000000000 -0700
+++ linux-2.6.22-rc-mm/Documentation/cpuidle/sysfs.txt 2007-06-06 11:35:37.000000000 -0700
@@ -4,14 +4,22 @@

cpuidle sysfs

-System global cpuidle information are under
+System global cpuidle related information and tunables are under
/sys/devices/system/cpu/cpuidle

The current interfaces in this directory has self-explanatory names:
+* current_driver_ro
+* current_governor_ro
+
+With cpuidle_sysfs_switch boot option (meant for developer testing)
+following objects are visible instead.
* available_drivers
* available_governors
* current_driver
* current_governor
+In this case user can switch the driver, governor at run time by writing
+onto current_driver and current_governor.
+

Per logical CPU specific cpuidle information are under
/sys/devices/system/cpu/cpuX/cpuidle
@@ -19,9 +27,9 @@

Under this percpu directory, there is a directory for each idle state supported
by the driver, which in turn has
-* latency
-* power
-* time
-* usage
+* latency : Latency to exit out of this idle state (in microseconds)
+* power : Power consumed while in this idle state (in milliwatts)
+* time : Total time spent in this idle state (in microseconds)
+* usage : Number of times this state was entered (count)


Index: linux-2.6.22-rc-mm/Documentation/cpuidle/governor.txt
===================================================================
--- linux-2.6.22-rc-mm.orig/Documentation/cpuidle/governor.txt 2007-06-06 11:33:25.000000000 -0700
+++ linux-2.6.22-rc-mm/Documentation/cpuidle/governor.txt 2007-06-06 11:33:34.000000000 -0700
@@ -11,12 +11,16 @@
cpuidle governor is policy routine that decides what idle state to enter at
any given time. cpuidle core uses different callbacks to governor while
handling idle entry.
-* select_state callback where governor can determine next idle state to enter
-* prepare_idle callback is called before entering an idle state
-* scan callback is called after a driver forces redetection of the states
+* select_state() callback where governor can determine next idle state to enter
+* prepare_idle() callback is called before entering an idle state
+* scan() callback is called after a driver forces redetection of the states

More than one governor can be registered at the same time and
-user can switch between drivers using /sysfs interface.
+user can switch between drivers using /sysfs interface (when supported).
+
+More than one governor part is supported for developers to easily experiment
+with different governors. By default, most optimal governor based on your
+kernel configuration and platform will be selected by cpuidle.

Interfaces:
int cpuidle_register_governor(struct cpuidle_governor *gov);
Index: linux-2.6.22-rc-mm/Documentation/cpuidle/core.txt
===================================================================
--- linux-2.6.22-rc-mm.orig/Documentation/cpuidle/core.txt 2007-06-06 11:33:25.000000000 -0700
+++ linux-2.6.22-rc-mm/Documentation/cpuidle/core.txt 2007-06-06 11:33:34.000000000 -0700
@@ -12,6 +12,6 @@
standardized infrastructure to support independent development of
governors and drivers.

-cpuidle resides under /drivers/cpuidle.
+cpuidle resides under drivers/cpuidle.


Index: linux-2.6.22-rc-mm/Documentation/cpuidle/driver.txt
===================================================================
--- linux-2.6.22-rc-mm.orig/Documentation/cpuidle/driver.txt 2007-06-06 11:33:25.000000000 -0700
+++ linux-2.6.22-rc-mm/Documentation/cpuidle/driver.txt 2007-06-06 11:33:34.000000000 -0700
@@ -7,16 +7,21 @@



-cpuidle driver supports capability detection for a particular system. The
-init and exit routines will be called for each online CPU, with a percpu
-cpuidle_driver object and driver should fill in cpuidle_states inside
-cpuidle_driver depending on the CPU capability.
+cpuidle driver hooks into the cpuidle infrastructure and does the
+architecture/platform dependent part of CPU idle states. Driver
+provides the platform idle state detection capability and also
+has mechanisms in place to support actusl entry-exit into a CPU idle state.
+
+cpuidle driver supports capability detection for a platform using the
+init and exit routines. They will be called for each online CPU, with a
+percpu cpuidle_driver object and driver should fill in cpuidle_states
+inside cpuidle_driver depending on the CPU capability.

Driver can handle dynamic state changes (like battery<->AC), by calling
force_redetect interface.

It is possible to have more than one driver registered at the same time and
-user can switch between drivers using /sysfs interface.
+user can switch between drivers using /sysfs interface (when enabled).

Interfaces:
int cpuidle_register_driver(struct cpuidle_driver *drv);
-
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