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 tristate 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 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 47config 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 56choice 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 64config 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 72config CPU_FREQ_DEFAULT_GOV_POWERSAVE 73 bool "powersave" 74 depends on EMBEDDED 75 select CPU_FREQ_GOV_POWERSAVE 76 help 77 Use the CPUFreq governor 'powersave' as default. This sets 78 the frequency statically to the lowest frequency supported by 79 the CPU. 80 81config CPU_FREQ_DEFAULT_GOV_USERSPACE 82 bool "userspace" 83 select CPU_FREQ_GOV_USERSPACE 84 help 85 Use the CPUFreq governor 'userspace' as default. This allows 86 you to set the CPU frequency manually or when a userspace 87 program shall be able to set the CPU dynamically without having 88 to enable the userspace governor manually. 89 90config CPU_FREQ_DEFAULT_GOV_ONDEMAND 91 bool "ondemand" 92 select CPU_FREQ_GOV_ONDEMAND 93 select CPU_FREQ_GOV_PERFORMANCE 94 help 95 Use the CPUFreq governor 'ondemand' as default. This allows 96 you to get a full dynamic frequency capable system by simply 97 loading your cpufreq low-level hardware driver. 98 Be aware that not all cpufreq drivers support the ondemand 99 governor. If unsure have a look at the help section of the 100 driver. Fallback governor will be the performance governor. 101 102config CPU_FREQ_DEFAULT_GOV_CONSERVATIVE 103 bool "conservative" 104 select CPU_FREQ_GOV_CONSERVATIVE 105 select CPU_FREQ_GOV_PERFORMANCE 106 help 107 Use the CPUFreq governor 'conservative' as default. This allows 108 you to get a full dynamic frequency capable system by simply 109 loading your cpufreq low-level hardware driver. 110 Be aware that not all cpufreq drivers support the conservative 111 governor. If unsure have a look at the help section of the 112 driver. Fallback governor will be the performance governor. 113endchoice 114 115config CPU_FREQ_GOV_PERFORMANCE 116 tristate "'performance' governor" 117 help 118 This cpufreq governor sets the frequency statically to the 119 highest available CPU frequency. 120 121 To compile this driver as a module, choose M here: the 122 module will be called cpufreq_performance. 123 124 If in doubt, say Y. 125 126config CPU_FREQ_GOV_POWERSAVE 127 tristate "'powersave' governor" 128 help 129 This cpufreq governor sets the frequency statically to the 130 lowest available CPU frequency. 131 132 To compile this driver as a module, choose M here: the 133 module will be called cpufreq_powersave. 134 135 If in doubt, say Y. 136 137config CPU_FREQ_GOV_USERSPACE 138 tristate "'userspace' governor for userspace frequency scaling" 139 help 140 Enable this cpufreq governor when you either want to set the 141 CPU frequency manually or when a userspace program shall 142 be able to set the CPU dynamically, like on LART 143 <http://www.lartmaker.nl/>. 144 145 To compile this driver as a module, choose M here: the 146 module will be called cpufreq_userspace. 147 148 For details, take a look at <file:Documentation/cpu-freq/>. 149 150 If in doubt, say Y. 151 152config CPU_FREQ_GOV_ONDEMAND 153 tristate "'ondemand' cpufreq policy governor" 154 select CPU_FREQ_TABLE 155 help 156 'ondemand' - This driver adds a dynamic cpufreq policy governor. 157 The governor does a periodic polling and 158 changes frequency based on the CPU utilization. 159 The support for this governor depends on CPU capability to 160 do fast frequency switching (i.e, very low latency frequency 161 transitions). 162 163 To compile this driver as a module, choose M here: the 164 module will be called cpufreq_ondemand. 165 166 For details, take a look at linux/Documentation/cpu-freq. 167 168 If in doubt, say N. 169 170config CPU_FREQ_GOV_CONSERVATIVE 171 tristate "'conservative' cpufreq governor" 172 depends on CPU_FREQ 173 help 174 'conservative' - this driver is rather similar to the 'ondemand' 175 governor both in its source code and its purpose, the difference is 176 its optimisation for better suitability in a battery powered 177 environment. The frequency is gracefully increased and decreased 178 rather than jumping to 100% when speed is required. 179 180 If you have a desktop machine then you should really be considering 181 the 'ondemand' governor instead, however if you are using a laptop, 182 PDA or even an AMD64 based computer (due to the unacceptable 183 step-by-step latency issues between the minimum and maximum frequency 184 transitions in the CPU) you will probably want to use this governor. 185 186 To compile this driver as a module, choose M here: the 187 module will be called cpufreq_conservative. 188 189 For details, take a look at linux/Documentation/cpu-freq. 190 191 If in doubt, say N. 192 193endif # CPU_FREQ 194