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