1 menu "CPU Frequency scaling"
4 bool "CPU Frequency scaling"
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.
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.
14 For details, take a look at <file:Documentation/cpu-freq>.
20 config CPU_FREQ_GOV_COMMON
23 config CPU_FREQ_BOOST_SW
28 tristate "CPU frequency translation statistics"
31 This driver exports CPU frequency statistics information through sysfs
34 To compile this driver as a module, choose M here: the
35 module will be called cpufreq_stats.
39 config CPU_FREQ_STAT_DETAILS
40 bool "CPU frequency translation statistics details"
41 depends on CPU_FREQ_STAT
43 This will show detail CPU frequency translation table in sysfs file
49 prompt "Default CPUFreq governor"
50 default CPU_FREQ_DEFAULT_GOV_USERSPACE if ARM_SA1100_CPUFREQ || ARM_SA1110_CPUFREQ
51 default CPU_FREQ_DEFAULT_GOV_PERFORMANCE
53 This option sets which CPUFreq governor shall be loaded at
54 startup. If in doubt, select 'performance'.
56 config CPU_FREQ_DEFAULT_GOV_PERFORMANCE
58 select CPU_FREQ_GOV_PERFORMANCE
60 Use the CPUFreq governor 'performance' as default. This sets
61 the frequency statically to the highest frequency supported by
64 config CPU_FREQ_DEFAULT_GOV_POWERSAVE
66 select CPU_FREQ_GOV_POWERSAVE
68 Use the CPUFreq governor 'powersave' as default. This sets
69 the frequency statically to the lowest frequency supported by
72 config CPU_FREQ_DEFAULT_GOV_USERSPACE
74 select CPU_FREQ_GOV_USERSPACE
76 Use the CPUFreq governor 'userspace' as default. This allows
77 you to set the CPU frequency manually or when a userspace
78 program shall be able to set the CPU dynamically without having
79 to enable the userspace governor manually.
81 config CPU_FREQ_DEFAULT_GOV_ONDEMAND
83 select CPU_FREQ_GOV_ONDEMAND
84 select CPU_FREQ_GOV_PERFORMANCE
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.
93 config CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
95 select CPU_FREQ_GOV_CONSERVATIVE
96 select CPU_FREQ_GOV_PERFORMANCE
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.
106 config CPU_FREQ_GOV_PERFORMANCE
107 tristate "'performance' governor"
109 This cpufreq governor sets the frequency statically to the
110 highest available CPU frequency.
112 To compile this driver as a module, choose M here: the
113 module will be called cpufreq_performance.
117 config CPU_FREQ_GOV_POWERSAVE
118 tristate "'powersave' governor"
120 This cpufreq governor sets the frequency statically to the
121 lowest available CPU frequency.
123 To compile this driver as a module, choose M here: the
124 module will be called cpufreq_powersave.
128 config CPU_FREQ_GOV_USERSPACE
129 tristate "'userspace' governor for userspace frequency scaling"
131 Enable this cpufreq governor when you either want to set the
132 CPU frequency manually or when a userspace program shall
133 be able to set the CPU dynamically, like on LART
134 <http://www.lartmaker.nl/>.
136 To compile this driver as a module, choose M here: the
137 module will be called cpufreq_userspace.
139 For details, take a look at <file:Documentation/cpu-freq/>.
143 config CPU_FREQ_GOV_ONDEMAND
144 tristate "'ondemand' cpufreq policy governor"
145 select CPU_FREQ_GOV_COMMON
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
154 To compile this driver as a module, choose M here: the
155 module will be called cpufreq_ondemand.
157 For details, take a look at linux/Documentation/cpu-freq.
161 config CPU_FREQ_GOV_CONSERVATIVE
162 tristate "'conservative' cpufreq governor"
164 select CPU_FREQ_GOV_COMMON
166 'conservative' - this driver is rather similar to the 'ondemand'
167 governor both in its source code and its purpose, the difference is
168 its optimisation for better suitability in a battery powered
169 environment. The frequency is gracefully increased and decreased
170 rather than jumping to 100% when speed is required.
172 If you have a desktop machine then you should really be considering
173 the 'ondemand' governor instead, however if you are using a laptop,
174 PDA or even an AMD64 based computer (due to the unacceptable
175 step-by-step latency issues between the minimum and maximum frequency
176 transitions in the CPU) you will probably want to use this governor.
178 To compile this driver as a module, choose M here: the
179 module will be called cpufreq_conservative.
181 For details, take a look at linux/Documentation/cpu-freq.
185 comment "CPU frequency scaling drivers"
188 tristate "Generic DT based cpufreq driver"
189 depends on HAVE_CLK && OF
190 # if CPU_THERMAL is on and THERMAL=m, CPUFREQ_DT cannot be =y:
191 depends on !CPU_THERMAL || THERMAL
194 This adds a generic DT based cpufreq driver for frequency management.
195 It supports both uniprocessor (UP) and symmetric multiprocessor (SMP)
196 systems which share clock and voltage across all CPUs.
201 source "drivers/cpufreq/Kconfig.x86"
205 source "drivers/cpufreq/Kconfig.arm"
209 source "drivers/cpufreq/Kconfig.powerpc"
213 config AVR32_AT32AP_CPUFREQ
214 bool "CPU frequency driver for AT32AP"
215 depends on PLATFORM_AT32AP
218 This enables the CPU frequency driver for AT32AP processors.
223 config IA64_ACPI_CPUFREQ
224 tristate "ACPI Processor P-States driver"
225 depends on ACPI_PROCESSOR
227 This driver adds a CPUFreq driver which utilizes the ACPI
228 Processor Performance States.
230 For details, take a look at <file:Documentation/cpu-freq/>.
236 config LOONGSON2_CPUFREQ
237 tristate "Loongson2 CPUFreq Driver"
239 This option adds a CPUFreq driver for loongson processors which
240 support software configurable cpu frequency.
242 Loongson2F and it's successors support this feature.
244 For details, take a look at <file:Documentation/cpu-freq/>.
248 config LOONGSON1_CPUFREQ
249 tristate "Loongson1 CPUFreq Driver"
251 This option adds a CPUFreq driver for loongson1 processors which
252 support software configurable cpu frequency.
254 For details, take a look at <file:Documentation/cpu-freq/>.
260 config SPARC_US3_CPUFREQ
261 tristate "UltraSPARC-III CPU Frequency driver"
263 This adds the CPUFreq driver for UltraSPARC-III processors.
265 For details, take a look at <file:Documentation/cpu-freq>.
269 config SPARC_US2E_CPUFREQ
270 tristate "UltraSPARC-IIe CPU Frequency driver"
272 This adds the CPUFreq driver for UltraSPARC-IIe processors.
274 For details, take a look at <file:Documentation/cpu-freq>.
281 tristate "SuperH CPU Frequency driver"
283 This adds the cpufreq driver for SuperH. Any CPU that supports
284 clock rate rounding through the clock framework can use this
285 driver. While it will make the kernel slightly larger, this is
286 harmless for CPUs that don't support rate rounding. The driver
287 will also generate a notice in the boot log before disabling
288 itself if the CPU in question is not capable of rate rounding.
290 For details, take a look at <file:Documentation/cpu-freq>.