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           To compile this driver as a module, choose M here: the
  43           module will be called cpufreq_stats.
  44
  45           If in doubt, say N.
  46
  47 config CPU_FREQ_STAT_DETAILS
  48         bool "CPU frequency translation statistics details"
  49         depends on CPU_FREQ_STAT
  50         help
  51           This will show detail CPU frequency translation table in sysfs file
  52           system.
  53
  54           If in doubt, say N.
  55
  56 choice
  57         prompt "Default CPUFreq governor"
  58         default CPU_FREQ_DEFAULT_GOV_USERSPACE if CPU_FREQ_SA1100 || CPU_FREQ_SA1110
  59         default CPU_FREQ_DEFAULT_GOV_PERFORMANCE
  60         help
  61           This option sets which CPUFreq governor shall be loaded at
  62           startup. If in doubt, select 'performance'.
  63
  64 config CPU_FREQ_DEFAULT_GOV_PERFORMANCE
  65         bool "performance"
  66         select CPU_FREQ_GOV_PERFORMANCE
  67         help
  68           Use the CPUFreq governor 'performance' as default. This sets
  69           the frequency statically to the highest frequency supported by
  70           the CPU.
  71
  72 config CPU_FREQ_DEFAULT_GOV_POWERSAVE
  73         bool "powersave"
  74         depends on EMBEDDED
  75         select CPU_FREQ_GOV_POWERSAVE
  76         help
  77           Use the CPUFreq governor 'powersave' as default. This sets
  78           the frequency statically to the lowest frequency supported by
  79           the CPU.
  80
  81 config CPU_FREQ_DEFAULT_GOV_USERSPACE
  82         bool "userspace"
  83         select CPU_FREQ_GOV_USERSPACE
  84         help
  85           Use the CPUFreq governor 'userspace' as default. This allows
  86           you to set the CPU frequency manually or when a userspace
  87           program shall be able to set the CPU dynamically without having
  88           to enable the userspace governor manually.
  89
  90 config CPU_FREQ_DEFAULT_GOV_ONDEMAND
  91         bool "ondemand"
  92         select CPU_FREQ_GOV_ONDEMAND
  93         select CPU_FREQ_GOV_PERFORMANCE
  94         help
  95           Use the CPUFreq governor 'ondemand' as default. This allows
  96           you to get a full dynamic frequency capable system by simply
  97           loading your cpufreq low-level hardware driver.
  98           Be aware that not all cpufreq drivers support the ondemand
  99           governor. If unsure have a look at the help section of the
 100           driver. Fallback governor will be the performance governor.
 101
 102 config CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
 103         bool "conservative"
 104         select CPU_FREQ_GOV_CONSERVATIVE
 105         select CPU_FREQ_GOV_PERFORMANCE
 106         help
 107           Use the CPUFreq governor 'conservative' as default. This allows
 108           you to get a full dynamic frequency capable system by simply
 109           loading your cpufreq low-level hardware driver.
 110           Be aware that not all cpufreq drivers support the conservative
 111           governor. If unsure have a look at the help section of the
 112           driver. Fallback governor will be the performance governor.
 113 endchoice
 114
 115 config CPU_FREQ_GOV_PERFORMANCE
 116         tristate "'performance' governor"
 117         help
 118           This cpufreq governor sets the frequency statically to the
 119           highest available CPU frequency.
 120
 121           To compile this driver as a module, choose M here: the
 122           module will be called cpufreq_performance.
 123
 124           If in doubt, say Y.
 125
 126 config CPU_FREQ_GOV_POWERSAVE
 127         tristate "'powersave' governor"
 128         help
 129           This cpufreq governor sets the frequency statically to the
 130           lowest available CPU frequency.
 131
 132           To compile this driver as a module, choose M here: the
 133           module will be called cpufreq_powersave.
 134
 135           If in doubt, say Y.
 136
 137 config CPU_FREQ_GOV_USERSPACE
 138         tristate "'userspace' governor for userspace frequency scaling"
 139         help
 140           Enable this cpufreq governor when you either want to set the
 141           CPU frequency manually or when a userspace program shall
 142           be able to set the CPU dynamically, like on LART
 143           <http://www.lartmaker.nl/>.
 144
 145           To compile this driver as a module, choose M here: the
 146           module will be called cpufreq_userspace.
 147
 148           For details, take a look at <file:Documentation/cpu-freq/>.
 149
 150           If in doubt, say Y.
 151
 152 config CPU_FREQ_GOV_ONDEMAND
 153         tristate "'ondemand' cpufreq policy governor"
 154         select CPU_FREQ_TABLE
 155         help
 156           'ondemand' - This driver adds a dynamic cpufreq policy governor.
 157           The governor does a periodic polling and
 158           changes frequency based on the CPU utilization.
 159           The support for this governor depends on CPU capability to
 160           do fast frequency switching (i.e, very low latency frequency
 161           transitions).
 162
 163           To compile this driver as a module, choose M here: the
 164           module will be called cpufreq_ondemand.
 165
 166           For details, take a look at linux/Documentation/cpu-freq.
 167
 168           If in doubt, say N.
 169
 170 config CPU_FREQ_GOV_CONSERVATIVE
 171         tristate "'conservative' cpufreq governor"
 172         depends on CPU_FREQ
 173         help
 174           'conservative' - this driver is rather similar to the 'ondemand'
 175           governor both in its source code and its purpose, the difference is
 176           its optimisation for better suitability in a battery powered
 177           environment.  The frequency is gracefully increased and decreased
 178           rather than jumping to 100% when speed is required.
 179
 180           If you have a desktop machine then you should really be considering
 181           the 'ondemand' governor instead, however if you are using a laptop,
 182           PDA or even an AMD64 based computer (due to the unacceptable
 183           step-by-step latency issues between the minimum and maximum frequency
 184           transitions in the CPU) you will probably want to use this governor.
 185
 186           To compile this driver as a module, choose M here: the
 187           module will be called cpufreq_conservative.
 188
 189           For details, take a look at linux/Documentation/cpu-freq.
 190
 191           If in doubt, say N.
 192
 193 endif   # CPU_FREQ