1menu "CPU Frequency scaling" 2 3config CPU_FREQ 4 bool "CPU Frequency scaling" 5 help 6 CPU Frequency scaling allows you to change the clock speed of 7 CPUs on the fly. This is a nice method to save power, because 8 the lower the CPU clock speed, the less power the CPU consumes. 9 10 Note that this driver doesn't automatically change the CPU 11 clock speed, you need to either enable a dynamic cpufreq governor 12 (see below) after boot, or use a userspace tool. 13 14 For details, take a look at <file:Documentation/cpu-freq>. 15 16 If in doubt, say N. 17 18if CPU_FREQ 19 20config CPU_FREQ_TABLE 21 tristate 22 23config CPU_FREQ_STAT 24 tristate "CPU frequency translation statistics" 25 select CPU_FREQ_TABLE 26 default y 27 help 28 This driver exports CPU frequency statistics information through sysfs 29 file system. 30 31 To compile this driver as a module, choose M here: the 32 module will be called cpufreq_stats. 33 34 If in doubt, say N. 35 36config 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 43 If in doubt, say N. 44 45choice 46 prompt "Default CPUFreq governor" 47 default CPU_FREQ_DEFAULT_GOV_USERSPACE if CPU_FREQ_SA1100 || CPU_FREQ_SA1110 48 default CPU_FREQ_DEFAULT_GOV_PERFORMANCE 49 help 50 This option sets which CPUFreq governor shall be loaded at 51 startup. If in doubt, select 'performance'. 52 53config CPU_FREQ_DEFAULT_GOV_PERFORMANCE 54 bool "performance" 55 select CPU_FREQ_GOV_PERFORMANCE 56 help 57 Use the CPUFreq governor 'performance' as default. This sets 58 the frequency statically to the highest frequency supported by 59 the CPU. 60 61config CPU_FREQ_DEFAULT_GOV_POWERSAVE 62 bool "powersave" 63 depends on EXPERT 64 select CPU_FREQ_GOV_POWERSAVE 65 help 66 Use the CPUFreq governor 'powersave' as default. This sets 67 the frequency statically to the lowest frequency supported by 68 the CPU. 69 70config CPU_FREQ_DEFAULT_GOV_USERSPACE 71 bool "userspace" 72 select CPU_FREQ_GOV_USERSPACE 73 help 74 Use the CPUFreq governor 'userspace' as default. This allows 75 you to set the CPU frequency manually or when a userspace 76 program shall be able to set the CPU dynamically without having 77 to enable the userspace governor manually. 78 79config CPU_FREQ_DEFAULT_GOV_ONDEMAND 80 bool "ondemand" 81 select CPU_FREQ_GOV_ONDEMAND 82 select CPU_FREQ_GOV_PERFORMANCE 83 help 84 Use the CPUFreq governor 'ondemand' as default. This allows 85 you to get a full dynamic frequency capable system by simply 86 loading your cpufreq low-level hardware driver. 87 Be aware that not all cpufreq drivers support the ondemand 88 governor. If unsure have a look at the help section of the 89 driver. Fallback governor will be the performance governor. 90 91config CPU_FREQ_DEFAULT_GOV_CONSERVATIVE 92 bool "conservative" 93 select CPU_FREQ_GOV_CONSERVATIVE 94 select CPU_FREQ_GOV_PERFORMANCE 95 help 96 Use the CPUFreq governor 'conservative' as default. This allows 97 you to get a full dynamic frequency capable system by simply 98 loading your cpufreq low-level hardware driver. 99 Be aware that not all cpufreq drivers support the conservative 100 governor. If unsure have a look at the help section of the 101 driver. Fallback governor will be the performance governor. 102endchoice 103 104config CPU_FREQ_GOV_PERFORMANCE 105 tristate "'performance' governor" 106 help 107 This cpufreq governor sets the frequency statically to the 108 highest available CPU frequency. 109 110 To compile this driver as a module, choose M here: the 111 module will be called cpufreq_performance. 112 113 If in doubt, say Y. 114 115config CPU_FREQ_GOV_POWERSAVE 116 tristate "'powersave' governor" 117 help 118 This cpufreq governor sets the frequency statically to the 119 lowest available CPU frequency. 120 121 To compile this driver as a module, choose M here: the 122 module will be called cpufreq_powersave. 123 124 If in doubt, say Y. 125 126config CPU_FREQ_GOV_USERSPACE 127 tristate "'userspace' governor for userspace frequency scaling" 128 help 129 Enable this cpufreq governor when you either want to set the 130 CPU frequency manually or when a userspace program shall 131 be able to set the CPU dynamically, like on LART 132 <http://www.lartmaker.nl/>. 133 134 To compile this driver as a module, choose M here: the 135 module will be called cpufreq_userspace. 136 137 For details, take a look at <file:Documentation/cpu-freq/>. 138 139 If in doubt, say Y. 140 141config CPU_FREQ_GOV_ONDEMAND 142 tristate "'ondemand' cpufreq policy governor" 143 select CPU_FREQ_TABLE 144 help 145 'ondemand' - This driver adds a dynamic cpufreq policy governor. 146 The governor does a periodic polling and 147 changes frequency based on the CPU utilization. 148 The support for this governor depends on CPU capability to 149 do fast frequency switching (i.e, very low latency frequency 150 transitions). 151 152 To compile this driver as a module, choose M here: the 153 module will be called cpufreq_ondemand. 154 155 For details, take a look at linux/Documentation/cpu-freq. 156 157 If in doubt, say N. 158 159config CPU_FREQ_GOV_CONSERVATIVE 160 tristate "'conservative' cpufreq governor" 161 depends on CPU_FREQ 162 help 163 'conservative' - this driver is rather similar to the 'ondemand' 164 governor both in its source code and its purpose, the difference is 165 its optimisation for better suitability in a battery powered 166 environment. The frequency is gracefully increased and decreased 167 rather than jumping to 100% when speed is required. 168 169 If you have a desktop machine then you should really be considering 170 the 'ondemand' governor instead, however if you are using a laptop, 171 PDA or even an AMD64 based computer (due to the unacceptable 172 step-by-step latency issues between the minimum and maximum frequency 173 transitions in the CPU) you will probably want to use this governor. 174 175 To compile this driver as a module, choose M here: the 176 module will be called cpufreq_conservative. 177 178 For details, take a look at linux/Documentation/cpu-freq. 179 180 If in doubt, say N. 181 182config GENERIC_CPUFREQ_CPU0 183 bool "Generic CPU0 cpufreq driver" 184 depends on HAVE_CLK && REGULATOR && PM_OPP && OF 185 select CPU_FREQ_TABLE 186 help 187 This adds a generic cpufreq driver for CPU0 frequency management. 188 It supports both uniprocessor (UP) and symmetric multiprocessor (SMP) 189 systems which share clock and voltage across all CPUs. 190 191 If in doubt, say N. 192 193menu "x86 CPU frequency scaling drivers" 194depends on X86 195source "drivers/cpufreq/Kconfig.x86" 196endmenu 197 198menu "ARM CPU frequency scaling drivers" 199depends on ARM 200source "drivers/cpufreq/Kconfig.arm" 201endmenu 202 203menu "PowerPC CPU frequency scaling drivers" 204depends on PPC32 || PPC64 205source "drivers/cpufreq/Kconfig.powerpc" 206endmenu 207 208endif 209endmenu 210