drivers/cpufreq/Kconfig

   1 config CPU_FREQ
   2         bool "CPU Frequency scaling"
   3         help
   4           CPU Frequency scaling allows you to change the clock speed of
   5           CPUs on the fly. This is a nice method to save power, because
   6           the lower the CPU clock speed, the less power the CPU consumes.
   7
   8           Note that this driver doesn't automatically change the CPU
   9           clock speed, you need to either enable a dynamic cpufreq governor
  10           (see below) after boot, or use a userspace tool.
  11
  12           To compile this driver as a module, choose M here: the
  13           module will be called cpufreq.
  14
  15           For details, take a look at <file:Documentation/cpu-freq>.
  16
  17           If in doubt, say N.
  18
  19 if CPU_FREQ
  20
  21 config CPU_FREQ_TABLE
  22         tristate
  23
  24 config CPU_FREQ_DEBUG
  25         bool "Enable CPUfreq debugging"
  26         help
  27           Say Y here to enable CPUfreq subsystem (including drivers)
  28           debugging. You will need to activate it via the kernel
  29           command line by passing
  30              cpufreq.debug=<value>
  31
  32           To get <value>, add
  33                1 to activate CPUfreq core debugging,
  34                2 to activate CPUfreq drivers debugging, and
  35                4 to activate CPUfreq governor debugging
  36
  37 config CPU_FREQ_STAT
  38         tristate "CPU frequency translation statistics"
  39         select CPU_FREQ_TABLE
  40         default y
  41         help
  42           This driver exports CPU frequency statistics information through sysfs
  43           file system.
  44
  45           To compile this driver as a module, choose M here: the
  46           module will be called cpufreq_stats.
  47
  48           If in doubt, say N.
  49
  50 config CPU_FREQ_STAT_DETAILS
  51         bool "CPU frequency translation statistics details"
  52         depends on CPU_FREQ_STAT
  53         help
  54           This will show detail CPU frequency translation table in sysfs file
  55           system.
  56
  57           If in doubt, say N.
  58
  59 # Note that it is not currently possible to set the other governors (such as ondemand)
  60 # as the default, since if they fail to initialise, cpufreq will be
  61 # left in an undefined state.
  62
  63 choice
  64         prompt "Default CPUFreq governor"
  65         default CPU_FREQ_DEFAULT_GOV_USERSPACE if CPU_FREQ_SA1100 || CPU_FREQ_SA1110
  66         default CPU_FREQ_DEFAULT_GOV_PERFORMANCE
  67         help
  68           This option sets which CPUFreq governor shall be loaded at
  69           startup. If in doubt, select 'performance'.
  70
  71 config CPU_FREQ_DEFAULT_GOV_PERFORMANCE
  72         bool "performance"
  73         select CPU_FREQ_GOV_PERFORMANCE
  74         help
  75           Use the CPUFreq governor 'performance' as default. This sets
  76           the frequency statically to the highest frequency supported by
  77           the CPU.
  78
  79 config CPU_FREQ_DEFAULT_GOV_USERSPACE
  80         bool "userspace"
  81         select CPU_FREQ_GOV_USERSPACE
  82         help
  83           Use the CPUFreq governor 'userspace' as default. This allows
  84           you to set the CPU frequency manually or when an userspace
  85           program shall be able to set the CPU dynamically without having
  86           to enable the userspace governor manually.
  87
  88 endchoice
  89
  90 config CPU_FREQ_GOV_PERFORMANCE
  91         tristate "'performance' governor"
  92         help
  93           This cpufreq governor sets the frequency statically to the
  94           highest available CPU frequency.
  95
  96           To compile this driver as a module, choose M here: the
  97           module will be called cpufreq_performance.
  98
  99           If in doubt, say Y.
 100
 101 config CPU_FREQ_GOV_POWERSAVE
 102         tristate "'powersave' governor"
 103         help
 104           This cpufreq governor sets the frequency statically to the
 105           lowest available CPU frequency.
 106
 107           To compile this driver as a module, choose M here: the
 108           module will be called cpufreq_powersave.
 109
 110           If in doubt, say Y.
 111
 112 config CPU_FREQ_GOV_USERSPACE
 113         tristate "'userspace' governor for userspace frequency scaling"
 114         help
 115           Enable this cpufreq governor when you either want to set the
 116           CPU frequency manually or when an userspace program shall
 117           be able to set the CPU dynamically, like on LART
 118           <http://www.lartmaker.nl/>.
 119
 120           To compile this driver as a module, choose M here: the
 121           module will be called cpufreq_userspace.
 122
 123           For details, take a look at <file:Documentation/cpu-freq/>.
 124
 125           If in doubt, say Y.
 126
 127 config CPU_FREQ_GOV_ONDEMAND
 128         tristate "'ondemand' cpufreq policy governor"
 129         select CPU_FREQ_TABLE
 130         help
 131           'ondemand' - This driver adds a dynamic cpufreq policy governor.
 132           The governor does a periodic polling and
 133           changes frequency based on the CPU utilization.
 134           The support for this governor depends on CPU capability to
 135           do fast frequency switching (i.e, very low latency frequency
 136           transitions).
 137
 138           To compile this driver as a module, choose M here: the
 139           module will be called cpufreq_ondemand.
 140
 141           For details, take a look at linux/Documentation/cpu-freq.
 142
 143           If in doubt, say N.
 144
 145 config CPU_FREQ_GOV_CONSERVATIVE
 146         tristate "'conservative' cpufreq governor"
 147         depends on CPU_FREQ
 148         help
 149           'conservative' - this driver is rather similar to the 'ondemand'
 150           governor both in its source code and its purpose, the difference is
 151           its optimisation for better suitability in a battery powered
 152           environment.  The frequency is gracefully increased and decreased
 153           rather than jumping to 100% when speed is required.
 154
 155           If you have a desktop machine then you should really be considering
 156           the 'ondemand' governor instead, however if you are using a laptop,
 157           PDA or even an AMD64 based computer (due to the unacceptable
 158           step-by-step latency issues between the minimum and maximum frequency
 159           transitions in the CPU) you will probably want to use this governor.
 160
 161           To compile this driver as a module, choose M here: the
 162           module will be called cpufreq_conservative.
 163
 164           For details, take a look at linux/Documentation/cpu-freq.
 165
 166           If in doubt, say N.
 167
 168 endif   # CPU_FREQ