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 choice
  60         prompt "Default CPUFreq governor"
  61         default CPU_FREQ_DEFAULT_GOV_USERSPACE if CPU_FREQ_SA1100 || CPU_FREQ_SA1110
  62         default CPU_FREQ_DEFAULT_GOV_PERFORMANCE
  63         help
  64           This option sets which CPUFreq governor shall be loaded at
  65           startup. If in doubt, select 'performance'.
  66
  67 config CPU_FREQ_DEFAULT_GOV_PERFORMANCE
  68         bool "performance"
  69         select CPU_FREQ_GOV_PERFORMANCE
  70         help
  71           Use the CPUFreq governor 'performance' as default. This sets
  72           the frequency statically to the highest frequency supported by
  73           the CPU.
  74
  75 config CPU_FREQ_DEFAULT_GOV_USERSPACE
  76         bool "userspace"
  77         select CPU_FREQ_GOV_USERSPACE
  78         help
  79           Use the CPUFreq governor 'userspace' as default. This allows
  80           you to set the CPU frequency manually or when an userspace
  81           program shall be able to set the CPU dynamically without having
  82           to enable the userspace governor manually.
  83
  84 config CPU_FREQ_DEFAULT_GOV_ONDEMAND
  85         bool "ondemand"
  86         select CPU_FREQ_GOV_ONDEMAND
  87         select CPU_FREQ_GOV_PERFORMANCE
  88         help
  89           Use the CPUFreq governor 'ondemand' as default. This allows
  90           you to get a full dynamic frequency capable system by simply
  91           loading your cpufreq low-level hardware driver.
  92           Be aware that not all cpufreq drivers support the ondemand
  93           governor. If unsure have a look at the help section of the
  94           driver. Fallback governor will be the performance governor.
  95
  96 config CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
  97         bool "conservative"
  98         select CPU_FREQ_GOV_CONSERVATIVE
  99         select CPU_FREQ_GOV_PERFORMANCE
 100         help
 101           Use the CPUFreq governor 'conservative' as default. This allows
 102           you to get a full dynamic frequency capable system by simply
 103           loading your cpufreq low-level hardware driver.
 104           Be aware that not all cpufreq drivers support the conservative
 105           governor. If unsure have a look at the help section of the
 106           driver. Fallback governor will be the performance governor.
 107 endchoice
 108
 109 config CPU_FREQ_GOV_PERFORMANCE
 110         tristate "'performance' governor"
 111         help
 112           This cpufreq governor sets the frequency statically to the
 113           highest available CPU frequency.
 114
 115           To compile this driver as a module, choose M here: the
 116           module will be called cpufreq_performance.
 117
 118           If in doubt, say Y.
 119
 120 config CPU_FREQ_GOV_POWERSAVE
 121         tristate "'powersave' governor"
 122         help
 123           This cpufreq governor sets the frequency statically to the
 124           lowest available CPU frequency.
 125
 126           To compile this driver as a module, choose M here: the
 127           module will be called cpufreq_powersave.
 128
 129           If in doubt, say Y.
 130
 131 config CPU_FREQ_GOV_USERSPACE
 132         tristate "'userspace' governor for userspace frequency scaling"
 133         help
 134           Enable this cpufreq governor when you either want to set the
 135           CPU frequency manually or when an userspace program shall
 136           be able to set the CPU dynamically, like on LART
 137           <http://www.lartmaker.nl/>.
 138
 139           To compile this driver as a module, choose M here: the
 140           module will be called cpufreq_userspace.
 141
 142           For details, take a look at <file:Documentation/cpu-freq/>.
 143
 144           If in doubt, say Y.
 145
 146 config CPU_FREQ_GOV_ONDEMAND
 147         tristate "'ondemand' cpufreq policy governor"
 148         select CPU_FREQ_TABLE
 149         help
 150           'ondemand' - This driver adds a dynamic cpufreq policy governor.
 151           The governor does a periodic polling and
 152           changes frequency based on the CPU utilization.
 153           The support for this governor depends on CPU capability to
 154           do fast frequency switching (i.e, very low latency frequency
 155           transitions).
 156
 157           To compile this driver as a module, choose M here: the
 158           module will be called cpufreq_ondemand.
 159
 160           For details, take a look at linux/Documentation/cpu-freq.
 161
 162           If in doubt, say N.
 163
 164 config CPU_FREQ_GOV_CONSERVATIVE
 165         tristate "'conservative' cpufreq governor"
 166         depends on CPU_FREQ
 167         help
 168           'conservative' - this driver is rather similar to the 'ondemand'
 169           governor both in its source code and its purpose, the difference is
 170           its optimisation for better suitability in a battery powered
 171           environment.  The frequency is gracefully increased and decreased
 172           rather than jumping to 100% when speed is required.
 173
 174           If you have a desktop machine then you should really be considering
 175           the 'ondemand' governor instead, however if you are using a laptop,
 176           PDA or even an AMD64 based computer (due to the unacceptable
 177           step-by-step latency issues between the minimum and maximum frequency
 178           transitions in the CPU) you will probably want to use this governor.
 179
 180           To compile this driver as a module, choose M here: the
 181           module will be called cpufreq_conservative.
 182
 183           For details, take a look at linux/Documentation/cpu-freq.
 184
 185           If in doubt, say N.
 186
 187 endif   # CPU_FREQ