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