Kconfig 6.2 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. To compile this driver as a module, choose M here: the
  34. module will be called cpufreq_stats.
  35. If in doubt, say N.
  36. config CPU_FREQ_STAT_DETAILS
  37. bool "CPU frequency translation statistics details"
  38. depends on CPU_FREQ_STAT
  39. help
  40. This will show detail CPU frequency translation table in sysfs file
  41. system.
  42. If in doubt, say N.
  43. choice
  44. prompt "Default CPUFreq governor"
  45. default CPU_FREQ_DEFAULT_GOV_USERSPACE if CPU_FREQ_SA1100 || CPU_FREQ_SA1110
  46. default CPU_FREQ_DEFAULT_GOV_PERFORMANCE
  47. help
  48. This option sets which CPUFreq governor shall be loaded at
  49. startup. If in doubt, select 'performance'.
  50. config CPU_FREQ_DEFAULT_GOV_PERFORMANCE
  51. bool "performance"
  52. select CPU_FREQ_GOV_PERFORMANCE
  53. help
  54. Use the CPUFreq governor 'performance' as default. This sets
  55. the frequency statically to the highest frequency supported by
  56. the CPU.
  57. config CPU_FREQ_DEFAULT_GOV_POWERSAVE
  58. bool "powersave"
  59. depends on EMBEDDED
  60. select CPU_FREQ_GOV_POWERSAVE
  61. help
  62. Use the CPUFreq governor 'powersave' as default. This sets
  63. the frequency statically to the lowest frequency supported by
  64. the CPU.
  65. config CPU_FREQ_DEFAULT_GOV_USERSPACE
  66. bool "userspace"
  67. select CPU_FREQ_GOV_USERSPACE
  68. help
  69. Use the CPUFreq governor 'userspace' as default. This allows
  70. you to set the CPU frequency manually or when an userspace
  71. program shall be able to set the CPU dynamically without having
  72. to enable the userspace governor manually.
  73. config CPU_FREQ_DEFAULT_GOV_ONDEMAND
  74. bool "ondemand"
  75. select CPU_FREQ_GOV_ONDEMAND
  76. select CPU_FREQ_GOV_PERFORMANCE
  77. help
  78. Use the CPUFreq governor 'ondemand' as default. This allows
  79. you to get a full dynamic frequency capable system by simply
  80. loading your cpufreq low-level hardware driver.
  81. Be aware that not all cpufreq drivers support the ondemand
  82. governor. If unsure have a look at the help section of the
  83. driver. Fallback governor will be the performance governor.
  84. config CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
  85. bool "conservative"
  86. select CPU_FREQ_GOV_CONSERVATIVE
  87. select CPU_FREQ_GOV_PERFORMANCE
  88. help
  89. Use the CPUFreq governor 'conservative' 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 conservative
  93. governor. If unsure have a look at the help section of the
  94. driver. Fallback governor will be the performance governor.
  95. endchoice
  96. config CPU_FREQ_GOV_PERFORMANCE
  97. tristate "'performance' governor"
  98. help
  99. This cpufreq governor sets the frequency statically to the
  100. highest available CPU frequency.
  101. To compile this driver as a module, choose M here: the
  102. module will be called cpufreq_performance.
  103. If in doubt, say Y.
  104. config CPU_FREQ_GOV_POWERSAVE
  105. tristate "'powersave' governor"
  106. help
  107. This cpufreq governor sets the frequency statically to the
  108. lowest available CPU frequency.
  109. To compile this driver as a module, choose M here: the
  110. module will be called cpufreq_powersave.
  111. If in doubt, say Y.
  112. config CPU_FREQ_GOV_USERSPACE
  113. tristate "'userspace' governor for userspace frequency scaling"
  114. help
  115. Enable this cpufreq governor when you either want to set the
  116. CPU frequency manually or when an userspace program shall
  117. be able to set the CPU dynamically, like on LART
  118. <http://www.lartmaker.nl/>.
  119. To compile this driver as a module, choose M here: the
  120. module will be called cpufreq_userspace.
  121. For details, take a look at <file:Documentation/cpu-freq/>.
  122. If in doubt, say Y.
  123. config CPU_FREQ_GOV_ONDEMAND
  124. tristate "'ondemand' cpufreq policy governor"
  125. select CPU_FREQ_TABLE
  126. help
  127. 'ondemand' - This driver adds a dynamic cpufreq policy governor.
  128. The governor does a periodic polling and
  129. changes frequency based on the CPU utilization.
  130. The support for this governor depends on CPU capability to
  131. do fast frequency switching (i.e, very low latency frequency
  132. transitions).
  133. To compile this driver as a module, choose M here: the
  134. module will be called cpufreq_ondemand.
  135. For details, take a look at linux/Documentation/cpu-freq.
  136. If in doubt, say N.
  137. config CPU_FREQ_GOV_CONSERVATIVE
  138. tristate "'conservative' cpufreq governor"
  139. depends on CPU_FREQ
  140. help
  141. 'conservative' - this driver is rather similar to the 'ondemand'
  142. governor both in its source code and its purpose, the difference is
  143. its optimisation for better suitability in a battery powered
  144. environment. The frequency is gracefully increased and decreased
  145. rather than jumping to 100% when speed is required.
  146. If you have a desktop machine then you should really be considering
  147. the 'ondemand' governor instead, however if you are using a laptop,
  148. PDA or even an AMD64 based computer (due to the unacceptable
  149. step-by-step latency issues between the minimum and maximum frequency
  150. transitions in the CPU) you will probably want to use this governor.
  151. To compile this driver as a module, choose M here: the
  152. module will be called cpufreq_conservative.
  153. For details, take a look at linux/Documentation/cpu-freq.
  154. If in doubt, say N.
  155. endif # CPU_FREQ