1config 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 16if CPU_FREQ 17 18config CPU_FREQ_TABLE 19 def_tristate m 20 21config 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 34config 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 42config CPU_FREQ_STAT_DETAILS 43 bool "CPU frequency translation statistics details" 44 depends on CPU_FREQ_STAT 45 help 46 This will show detail CPU frequency translation table in sysfs file 47 system 48 49choice 50 prompt "Default CPUFreq governor" 51 default CPU_FREQ_DEFAULT_GOV_USERSPACE if CPU_FREQ_SA1100 || CPU_FREQ_SA1110 52 default CPU_FREQ_DEFAULT_GOV_PERFORMANCE 53 help 54 This option sets which CPUFreq governor shall be loaded at 55 startup. If in doubt, select 'performance'. 56 57config CPU_FREQ_DEFAULT_GOV_PERFORMANCE 58 bool "performance" 59 select CPU_FREQ_GOV_PERFORMANCE 60 help 61 Use the CPUFreq governor 'performance' as default. This sets 62 the frequency statically to the highest frequency supported by 63 the CPU. 64 65config 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 74endchoice 75 76config CPU_FREQ_GOV_PERFORMANCE 77 tristate "'performance' governor" 78 help 79 This cpufreq governor sets the frequency statically to the 80 highest available CPU frequency. 81 82 If in doubt, say Y. 83 84config CPU_FREQ_GOV_POWERSAVE 85 tristate "'powersave' governor" 86 help 87 This cpufreq governor sets the frequency statically to the 88 lowest available CPU frequency. 89 90 If in doubt, say Y. 91 92config CPU_FREQ_GOV_USERSPACE 93 tristate "'userspace' governor for userspace frequency scaling" 94 help 95 Enable this cpufreq governor when you either want to set the 96 CPU frequency manually or when an userspace program shall 97 be able to set the CPU dynamically, like on LART 98 <http://www.lart.tudelft.nl/> 99 100 For details, take a look at <file:Documentation/cpu-freq/>. 101 102 If in doubt, say Y. 103 104config CPU_FREQ_GOV_ONDEMAND 105 tristate "'ondemand' cpufreq policy governor" 106 help 107 'ondemand' - This driver adds a dynamic cpufreq policy governor. 108 The governor does a periodic polling and 109 changes frequency based on the CPU utilization. 110 The support for this governor depends on CPU capability to 111 do fast frequency switching (i.e, very low latency frequency 112 transitions). 113 114 For details, take a look at linux/Documentation/cpu-freq. 115 116 If in doubt, say N. 117 118endif # CPU_FREQ 119