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authorRussell King <rmk+kernel@arm.linux.org.uk>2011-12-05 23:20:17 +0000
committerRussell King <rmk+kernel@arm.linux.org.uk>2011-12-05 23:20:17 +0000
commit742eaa6a6e356a16788ce6530271de89bc4f8fb5 (patch)
tree12fc040daab06ac796c61c1d92bfad9bb054d1c1 /drivers/devfreq/Kconfig
parentba8bb18a03f8c7508565c385576a5431a4ad804a (diff)
parentae72fd588a2b302222769b44775912b83f0785eb (diff)
downloadlinux-rt-742eaa6a6e356a16788ce6530271de89bc4f8fb5.tar.gz
Merge branch 'for-rmk' of git://git.kernel.org/pub/scm/linux/kernel/git/will/linux into devel-stable
Conflicts: arch/arm/common/gic.c arch/arm/plat-omap/include/plat/common.h
Diffstat (limited to 'drivers/devfreq/Kconfig')
-rw-r--r--drivers/devfreq/Kconfig41
1 files changed, 17 insertions, 24 deletions
diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
index 643b055ed3cd..8f0491037080 100644
--- a/drivers/devfreq/Kconfig
+++ b/drivers/devfreq/Kconfig
@@ -1,36 +1,29 @@
-config ARCH_HAS_DEVFREQ
- bool
- depends on ARCH_HAS_OPP
- help
- Denotes that the architecture supports DEVFREQ. If the architecture
- supports multiple OPP entries per device and the frequency of the
- devices with OPPs may be altered dynamically, the architecture
- supports DEVFREQ.
-
menuconfig PM_DEVFREQ
bool "Generic Dynamic Voltage and Frequency Scaling (DVFS) support"
- depends on PM_OPP && ARCH_HAS_DEVFREQ
help
- With OPP support, a device may have a list of frequencies and
- voltages available. DEVFREQ, a generic DVFS framework can be
- registered for a device with OPP support in order to let the
- governor provided to DEVFREQ choose an operating frequency
- based on the OPP's list and the policy given with DEVFREQ.
+ A device may have a list of frequencies and voltages available.
+ devfreq, a generic DVFS framework can be registered for a device
+ in order to let the governor provided to devfreq choose an
+ operating frequency based on the device driver's policy.
- Each device may have its own governor and policy. DEVFREQ can
+ Each device may have its own governor and policy. Devfreq can
reevaluate the device state periodically and/or based on the
- OPP list changes (each frequency/voltage pair in OPP may be
- disabled or enabled).
+ notification to "nb", a notifier block, of devfreq.
- Like some CPUs with CPUFREQ, a device may have multiple clocks.
+ Like some CPUs with CPUfreq, a device may have multiple clocks.
However, because the clock frequencies of a single device are
- determined by the single device's state, an instance of DEVFREQ
+ determined by the single device's state, an instance of devfreq
is attached to a single device and returns a "representative"
- clock frequency from the OPP of the device, which is also attached
- to a device by 1-to-1. The device registering DEVFREQ takes the
- responsiblity to "interpret" the frequency listed in OPP and
+ clock frequency of the device, which is also attached
+ to a device by 1-to-1. The device registering devfreq takes the
+ responsiblity to "interpret" the representative frequency and
to set its every clock accordingly with the "target" callback
- given to DEVFREQ.
+ given to devfreq.
+
+ When OPP is used with the devfreq device, it is recommended to
+ register devfreq's nb to the OPP's notifier head. If OPP is
+ used with the devfreq device, you may use OPP helper
+ functions defined in devfreq.h.
if PM_DEVFREQ