1 menu "CPU Frequency scaling"
4 bool "CPU Frequency scaling"
7 CPU Frequency scaling allows you to change the clock speed of
8 CPUs on the fly. This is a nice method to save power, because
9 the lower the CPU clock speed, the less power the CPU consumes.
11 Note that this driver doesn't automatically change the CPU
12 clock speed, you need to either enable a dynamic cpufreq governor
13 (see below) after boot, or use a userspace tool.
15 For details, take a look at <file:Documentation/cpu-freq>.
24 config CPU_FREQ_GOV_COMMON
28 tristate "CPU frequency translation statistics"
32 This driver exports CPU frequency statistics information through sysfs
35 To compile this driver as a module, choose M here: the
36 module will be called cpufreq_stats.
40 config CPU_FREQ_STAT_DETAILS
41 bool "CPU frequency translation statistics details"
42 depends on CPU_FREQ_STAT
44 This will show detail CPU frequency translation table in sysfs file
50 prompt "Default CPUFreq governor"
51 default CPU_FREQ_DEFAULT_GOV_USERSPACE if ARM_SA1100_CPUFREQ || ARM_SA1110_CPUFREQ
52 default CPU_FREQ_DEFAULT_GOV_PERFORMANCE
54 This option sets which CPUFreq governor shall be loaded at
55 startup. If in doubt, select 'performance'.
57 config CPU_FREQ_DEFAULT_GOV_PERFORMANCE
59 select CPU_FREQ_GOV_PERFORMANCE
61 Use the CPUFreq governor 'performance' as default. This sets
62 the frequency statically to the highest frequency supported by
65 config CPU_FREQ_DEFAULT_GOV_POWERSAVE
68 select CPU_FREQ_GOV_POWERSAVE
70 Use the CPUFreq governor 'powersave' as default. This sets
71 the frequency statically to the lowest frequency supported by
74 config CPU_FREQ_DEFAULT_GOV_USERSPACE
76 select CPU_FREQ_GOV_USERSPACE
78 Use the CPUFreq governor 'userspace' as default. This allows
79 you to set the CPU frequency manually or when a userspace
80 program shall be able to set the CPU dynamically without having
81 to enable the userspace governor manually.
83 config CPU_FREQ_DEFAULT_GOV_ONDEMAND
85 select CPU_FREQ_GOV_ONDEMAND
86 select CPU_FREQ_GOV_PERFORMANCE
88 Use the CPUFreq governor 'ondemand' as default. This allows
89 you to get a full dynamic frequency capable system by simply
90 loading your cpufreq low-level hardware driver.
91 Be aware that not all cpufreq drivers support the ondemand
92 governor. If unsure have a look at the help section of the
93 driver. Fallback governor will be the performance governor.
95 config CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
97 select CPU_FREQ_GOV_CONSERVATIVE
98 select CPU_FREQ_GOV_PERFORMANCE
100 Use the CPUFreq governor 'conservative' as default. This allows
101 you to get a full dynamic frequency capable system by simply
102 loading your cpufreq low-level hardware driver.
103 Be aware that not all cpufreq drivers support the conservative
104 governor. If unsure have a look at the help section of the
105 driver. Fallback governor will be the performance governor.
108 config CPU_FREQ_GOV_PERFORMANCE
109 tristate "'performance' governor"
111 This cpufreq governor sets the frequency statically to the
112 highest available CPU frequency.
114 To compile this driver as a module, choose M here: the
115 module will be called cpufreq_performance.
119 config CPU_FREQ_GOV_POWERSAVE
120 tristate "'powersave' governor"
122 This cpufreq governor sets the frequency statically to the
123 lowest available CPU frequency.
125 To compile this driver as a module, choose M here: the
126 module will be called cpufreq_powersave.
130 config CPU_FREQ_GOV_USERSPACE
131 tristate "'userspace' governor for userspace frequency scaling"
133 Enable this cpufreq governor when you either want to set the
134 CPU frequency manually or when a userspace program shall
135 be able to set the CPU dynamically, like on LART
136 <http://www.lartmaker.nl/>.
138 To compile this driver as a module, choose M here: the
139 module will be called cpufreq_userspace.
141 For details, take a look at <file:Documentation/cpu-freq/>.
145 config CPU_FREQ_GOV_ONDEMAND
146 tristate "'ondemand' cpufreq policy governor"
147 select CPU_FREQ_TABLE
148 select CPU_FREQ_GOV_COMMON
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
157 To compile this driver as a module, choose M here: the
158 module will be called cpufreq_ondemand.
160 For details, take a look at linux/Documentation/cpu-freq.
164 config CPU_FREQ_GOV_CONSERVATIVE
165 tristate "'conservative' cpufreq governor"
167 select CPU_FREQ_GOV_COMMON
169 'conservative' - this driver is rather similar to the 'ondemand'
170 governor both in its source code and its purpose, the difference is
171 its optimisation for better suitability in a battery powered
172 environment. The frequency is gracefully increased and decreased
173 rather than jumping to 100% when speed is required.
175 If you have a desktop machine then you should really be considering
176 the 'ondemand' governor instead, however if you are using a laptop,
177 PDA or even an AMD64 based computer (due to the unacceptable
178 step-by-step latency issues between the minimum and maximum frequency
179 transitions in the CPU) you will probably want to use this governor.
181 To compile this driver as a module, choose M here: the
182 module will be called cpufreq_conservative.
184 For details, take a look at linux/Documentation/cpu-freq.
188 config GENERIC_CPUFREQ_CPU0
189 tristate "Generic CPU0 cpufreq driver"
190 depends on HAVE_CLK && REGULATOR && PM_OPP && OF
191 select CPU_FREQ_TABLE
193 This adds a generic cpufreq driver for CPU0 frequency management.
194 It supports both uniprocessor (UP) and symmetric multiprocessor (SMP)
195 systems which share clock and voltage across all CPUs.
199 menu "x86 CPU frequency scaling drivers"
201 source "drivers/cpufreq/Kconfig.x86"
204 menu "ARM CPU frequency scaling drivers"
206 source "drivers/cpufreq/Kconfig.arm"
209 menu "AVR32 CPU frequency scaling drivers"
212 config AVR32_AT32AP_CPUFREQ
213 bool "CPU frequency driver for AT32AP"
214 depends on PLATFORM_AT32AP
217 This enables the CPU frequency driver for AT32AP processors.
222 menu "CPUFreq processor drivers"
225 config IA64_ACPI_CPUFREQ
226 tristate "ACPI Processor P-States driver"
227 select CPU_FREQ_TABLE
228 depends on ACPI_PROCESSOR
230 This driver adds a CPUFreq driver which utilizes the ACPI
231 Processor Performance States.
233 For details, take a look at <file:Documentation/cpu-freq/>.
239 menu "MIPS CPUFreq processor drivers"
242 config LOONGSON2_CPUFREQ
243 tristate "Loongson2 CPUFreq Driver"
244 select CPU_FREQ_TABLE
246 This option adds a CPUFreq driver for loongson processors which
247 support software configurable cpu frequency.
249 Loongson2F and it's successors support this feature.
251 For details, take a look at <file:Documentation/cpu-freq/>.
257 menu "PowerPC CPU frequency scaling drivers"
258 depends on PPC32 || PPC64
259 source "drivers/cpufreq/Kconfig.powerpc"
262 menu "SPARC CPU frequency scaling drivers"
264 config SPARC_US3_CPUFREQ
265 tristate "UltraSPARC-III CPU Frequency driver"
266 select CPU_FREQ_TABLE
268 This adds the CPUFreq driver for UltraSPARC-III processors.
270 For details, take a look at <file:Documentation/cpu-freq>.
274 config SPARC_US2E_CPUFREQ
275 tristate "UltraSPARC-IIe CPU Frequency driver"
276 select CPU_FREQ_TABLE
278 This adds the CPUFreq driver for UltraSPARC-IIe processors.
280 For details, take a look at <file:Documentation/cpu-freq>.
285 menu "SH CPU Frequency scaling"
288 tristate "SuperH CPU Frequency driver"
289 select CPU_FREQ_TABLE
291 This adds the cpufreq driver for SuperH. Any CPU that supports
292 clock rate rounding through the clock framework can use this
293 driver. While it will make the kernel slightly larger, this is
294 harmless for CPUs that don't support rate rounding. The driver
295 will also generate a notice in the boot log before disabling
296 itself if the CPU in question is not capable of rate rounding.
298 For details, take a look at <file:Documentation/cpu-freq>.