xref: /linux/drivers/cpufreq/Kconfig (revision f0ec313a89a7377f440c815f82b0370bd67f62c6)

config CPU_FREQ
	bool "CPU Frequency scaling"
	help
	  CPU Frequency scaling allows you to change the clock speed of
	  CPUs on the fly. This is a nice method to save power, because
	  the lower the CPU clock speed, the less power the CPU consumes.

	  Note that this driver doesn't automatically change the CPU
	  clock speed, you need to either enable a dynamic cpufreq governor
	  (see below) after boot, or use a userspace tool.

	  For details, take a look at <file:Documentation/cpu-freq>.

	  If in doubt, say N.

if CPU_FREQ

config CPU_FREQ_TABLE
       tristate

config CPU_FREQ_DEBUG
	bool "Enable CPUfreq debugging"
	help
	  Say Y here to enable CPUfreq subsystem (including drivers)
	  debugging. You will need to activate it via the kernel
	  command line by passing
	     cpufreq.debug=<value>

	  To get <value>, add
	       1 to activate CPUfreq core debugging,
	       2 to activate CPUfreq drivers debugging, and
	       4 to activate CPUfreq governor debugging

config CPU_FREQ_STAT
       tristate "CPU frequency translation statistics"
       select CPU_FREQ_TABLE
       default y
       help
         This driver exports CPU frequency statistics information through sysfs
         file system

config CPU_FREQ_STAT_DETAILS
       bool "CPU frequency translation statistics details"
       depends on CPU_FREQ_STAT
       help
         This will show detail CPU frequency translation table in sysfs file
         system

# Note that it is not currently possible to set the other governors (such as ondemand)
# as the default, since if they fail to initialise, cpufreq will be
# left in an undefined state.

choice
	prompt "Default CPUFreq governor"
	default CPU_FREQ_DEFAULT_GOV_USERSPACE if CPU_FREQ_SA1100 || CPU_FREQ_SA1110
	default CPU_FREQ_DEFAULT_GOV_PERFORMANCE
	help
	  This option sets which CPUFreq governor shall be loaded at
	  startup. If in doubt, select 'performance'.

config CPU_FREQ_DEFAULT_GOV_PERFORMANCE
	bool "performance"
	select CPU_FREQ_GOV_PERFORMANCE
	help
	  Use the CPUFreq governor 'performance' as default. This sets
	  the frequency statically to the highest frequency supported by
	  the CPU.

config CPU_FREQ_DEFAULT_GOV_USERSPACE
	bool "userspace"
	select CPU_FREQ_GOV_USERSPACE
	help
	  Use the CPUFreq governor 'userspace' as default. This allows
	  you to set the CPU frequency manually or when an userspace
	  program shall be able to set the CPU dynamically without having
	  to enable the userspace governor manually.

endchoice

config CPU_FREQ_GOV_PERFORMANCE
       tristate "'performance' governor"
       help
	  This cpufreq governor sets the frequency statically to the
	  highest available CPU frequency.

	  If in doubt, say Y.

config CPU_FREQ_GOV_POWERSAVE
       tristate "'powersave' governor"
       help
	  This cpufreq governor sets the frequency statically to the
	  lowest available CPU frequency.

	  If in doubt, say Y.

config CPU_FREQ_GOV_USERSPACE
       tristate "'userspace' governor for userspace frequency scaling"
       help
	  Enable this cpufreq governor when you either want to set the
	  CPU frequency manually or when an userspace program shall
	  be able to set the CPU dynamically, like on LART
	  <http://www.lartmaker.nl/>.

	  For details, take a look at <file:Documentation/cpu-freq/>.

	  If in doubt, say Y.

config CPU_FREQ_GOV_ONDEMAND
	tristate "'ondemand' cpufreq policy governor"
	select CPU_FREQ_TABLE
	help
	  'ondemand' - This driver adds a dynamic cpufreq policy governor.
	  The governor does a periodic polling and
	  changes frequency based on the CPU utilization.
	  The support for this governor depends on CPU capability to
	  do fast frequency switching (i.e, very low latency frequency
	  transitions).

	  For details, take a look at linux/Documentation/cpu-freq.

	  If in doubt, say N.

config CPU_FREQ_GOV_CONSERVATIVE
	tristate "'conservative' cpufreq governor"
	depends on CPU_FREQ
	help
	  'conservative' - this driver is rather similar to the 'ondemand'
	  governor both in its source code and its purpose, the difference is
	  its optimisation for better suitability in a battery powered
	  environment.  The frequency is gracefully increased and decreased
	  rather than jumping to 100% when speed is required.

	  If you have a desktop machine then you should really be considering
	  the 'ondemand' governor instead, however if you are using a laptop,
	  PDA or even an AMD64 based computer (due to the unacceptable
	  step-by-step latency issues between the minimum and maximum frequency
	  transitions in the CPU) you will probably want to use this governor.

	  For details, take a look at linux/Documentation/cpu-freq.

	  If in doubt, say N.

endif	# CPU_FREQ