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 To compile this driver as a module, choose M here: the 13 module will be called cpufreq. 14 15 For details, take a look at <file:Documentation/cpu-freq>. 16 17 If in doubt, say N. 18 19if CPU_FREQ 20 21config CPU_FREQ_TABLE 22 tristate 23 24config CPU_FREQ_DEBUG 25 bool "Enable CPUfreq debugging" 26 help 27 Say Y here to enable CPUfreq subsystem (including drivers) 28 debugging. You will need to activate it via the kernel 29 command line by passing 30 cpufreq.debug=<value> 31 32 To get <value>, add 33 1 to activate CPUfreq core debugging, 34 2 to activate CPUfreq drivers debugging, and 35 4 to activate CPUfreq governor debugging 36 37config CPU_FREQ_STAT 38 tristate "CPU frequency translation statistics" 39 select CPU_FREQ_TABLE 40 default y 41 help 42 This driver exports CPU frequency statistics information through sysfs 43 file system. 44 45 To compile this driver as a module, choose M here: the 46 module will be called cpufreq_stats. 47 48 If in doubt, say N. 49 50config CPU_FREQ_STAT_DETAILS 51 bool "CPU frequency translation statistics details" 52 depends on CPU_FREQ_STAT 53 help 54 This will show detail CPU frequency translation table in sysfs file 55 system. 56 57 If in doubt, say N. 58 59choice 60 prompt "Default CPUFreq governor" 61 default CPU_FREQ_DEFAULT_GOV_USERSPACE if CPU_FREQ_SA1100 || CPU_FREQ_SA1110 62 default CPU_FREQ_DEFAULT_GOV_PERFORMANCE 63 help 64 This option sets which CPUFreq governor shall be loaded at 65 startup. If in doubt, select 'performance'. 66 67config CPU_FREQ_DEFAULT_GOV_PERFORMANCE 68 bool "performance" 69 select CPU_FREQ_GOV_PERFORMANCE 70 help 71 Use the CPUFreq governor 'performance' as default. This sets 72 the frequency statically to the highest frequency supported by 73 the CPU. 74 75config CPU_FREQ_DEFAULT_GOV_USERSPACE 76 bool "userspace" 77 select CPU_FREQ_GOV_USERSPACE 78 help 79 Use the CPUFreq governor 'userspace' as default. This allows 80 you to set the CPU frequency manually or when an userspace 81 program shall be able to set the CPU dynamically without having 82 to enable the userspace governor manually. 83 84config CPU_FREQ_DEFAULT_GOV_ONDEMAND 85 bool "ondemand" 86 select CPU_FREQ_GOV_ONDEMAND 87 select CPU_FREQ_GOV_PERFORMANCE 88 help 89 Use the CPUFreq governor 'ondemand' 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 ondemand 93 governor. If unsure have a look at the help section of the 94 driver. Fallback governor will be the performance governor. 95 96config CPU_FREQ_DEFAULT_GOV_CONSERVATIVE 97 bool "conservative" 98 select CPU_FREQ_GOV_CONSERVATIVE 99 select CPU_FREQ_GOV_PERFORMANCE 100 help 101 Use the CPUFreq governor 'conservative' as default. This allows 102 you to get a full dynamic frequency capable system by simply 103 loading your cpufreq low-level hardware driver. 104 Be aware that not all cpufreq drivers support the conservative 105 governor. If unsure have a look at the help section of the 106 driver. Fallback governor will be the performance governor. 107endchoice 108 109config CPU_FREQ_GOV_PERFORMANCE 110 tristate "'performance' governor" 111 help 112 This cpufreq governor sets the frequency statically to the 113 highest available CPU frequency. 114 115 To compile this driver as a module, choose M here: the 116 module will be called cpufreq_performance. 117 118 If in doubt, say Y. 119 120config CPU_FREQ_GOV_POWERSAVE 121 tristate "'powersave' governor" 122 help 123 This cpufreq governor sets the frequency statically to the 124 lowest available CPU frequency. 125 126 To compile this driver as a module, choose M here: the 127 module will be called cpufreq_powersave. 128 129 If in doubt, say Y. 130 131config CPU_FREQ_GOV_USERSPACE 132 tristate "'userspace' governor for userspace frequency scaling" 133 help 134 Enable this cpufreq governor when you either want to set the 135 CPU frequency manually or when an userspace program shall 136 be able to set the CPU dynamically, like on LART 137 <http://www.lartmaker.nl/>. 138 139 To compile this driver as a module, choose M here: the 140 module will be called cpufreq_userspace. 141 142 For details, take a look at <file:Documentation/cpu-freq/>. 143 144 If in doubt, say Y. 145 146config CPU_FREQ_GOV_ONDEMAND 147 tristate "'ondemand' cpufreq policy governor" 148 select CPU_FREQ_TABLE 149 help 150 'ondemand' - This driver adds a dynamic cpufreq policy governor. 151 The governor does a periodic polling and 152 changes frequency based on the CPU utilization. 153 The support for this governor depends on CPU capability to 154 do fast frequency switching (i.e, very low latency frequency 155 transitions). 156 157 To compile this driver as a module, choose M here: the 158 module will be called cpufreq_ondemand. 159 160 For details, take a look at linux/Documentation/cpu-freq. 161 162 If in doubt, say N. 163 164config CPU_FREQ_GOV_CONSERVATIVE 165 tristate "'conservative' cpufreq governor" 166 depends on CPU_FREQ 167 help 168 'conservative' - this driver is rather similar to the 'ondemand' 169 governor both in its source code and its purpose, the difference is 170 its optimisation for better suitability in a battery powered 171 environment. The frequency is gracefully increased and decreased 172 rather than jumping to 100% when speed is required. 173 174 If you have a desktop machine then you should really be considering 175 the 'ondemand' governor instead, however if you are using a laptop, 176 PDA or even an AMD64 based computer (due to the unacceptable 177 step-by-step latency issues between the minimum and maximum frequency 178 transitions in the CPU) you will probably want to use this governor. 179 180 To compile this driver as a module, choose M here: the 181 module will be called cpufreq_conservative. 182 183 For details, take a look at linux/Documentation/cpu-freq. 184 185 If in doubt, say N. 186 187endif # CPU_FREQ 188