Kconfig 4.6 KB

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