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