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
24 tristate "CPU frequency translation statistics"
27 This driver exports CPU frequency statistics information through sysfs
30 To compile this driver as a module, choose M here: the
31 module will be called cpufreq_stats.
35 config CPU_FREQ_STAT_DETAILS
36 bool "CPU frequency translation statistics details"
37 depends on CPU_FREQ_STAT
39 This will show detail CPU frequency translation table in sysfs file
45 prompt "Default CPUFreq governor"
46 default CPU_FREQ_DEFAULT_GOV_USERSPACE if ARM_SA1100_CPUFREQ || ARM_SA1110_CPUFREQ
47 default CPU_FREQ_DEFAULT_GOV_PERFORMANCE
49 This option sets which CPUFreq governor shall be loaded at
50 startup. If in doubt, select 'performance'.
52 config CPU_FREQ_DEFAULT_GOV_PERFORMANCE
54 select CPU_FREQ_GOV_PERFORMANCE
56 Use the CPUFreq governor 'performance' as default. This sets
57 the frequency statically to the highest frequency supported by
60 config CPU_FREQ_DEFAULT_GOV_POWERSAVE
63 select CPU_FREQ_GOV_POWERSAVE
65 Use the CPUFreq governor 'powersave' as default. This sets
66 the frequency statically to the lowest frequency supported by
69 config CPU_FREQ_DEFAULT_GOV_USERSPACE
71 select CPU_FREQ_GOV_USERSPACE
73 Use the CPUFreq governor 'userspace' as default. This allows
74 you to set the CPU frequency manually or when a userspace
75 program shall be able to set the CPU dynamically without having
76 to enable the userspace governor manually.
78 config CPU_FREQ_DEFAULT_GOV_ONDEMAND
80 select CPU_FREQ_GOV_ONDEMAND
81 select CPU_FREQ_GOV_PERFORMANCE
83 Use the CPUFreq governor 'ondemand' as default. This allows
84 you to get a full dynamic frequency capable system by simply
85 loading your cpufreq low-level hardware driver.
86 Be aware that not all cpufreq drivers support the ondemand
87 governor. If unsure have a look at the help section of the
88 driver. Fallback governor will be the performance governor.
90 config CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
92 select CPU_FREQ_GOV_CONSERVATIVE
93 select CPU_FREQ_GOV_PERFORMANCE
95 Use the CPUFreq governor 'conservative' 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 conservative
99 governor. If unsure have a look at the help section of the
100 driver. Fallback governor will be the performance governor.
103 config CPU_FREQ_GOV_PERFORMANCE
104 tristate "'performance' governor"
106 This cpufreq governor sets the frequency statically to the
107 highest available CPU frequency.
109 To compile this driver as a module, choose M here: the
110 module will be called cpufreq_performance.
114 config CPU_FREQ_GOV_POWERSAVE
115 tristate "'powersave' governor"
117 This cpufreq governor sets the frequency statically to the
118 lowest available CPU frequency.
120 To compile this driver as a module, choose M here: the
121 module will be called cpufreq_powersave.
125 config CPU_FREQ_GOV_USERSPACE
126 tristate "'userspace' governor for userspace frequency scaling"
128 Enable this cpufreq governor when you either want to set the
129 CPU frequency manually or when a userspace program shall
130 be able to set the CPU dynamically, like on LART
131 <http://www.lartmaker.nl/>.
133 To compile this driver as a module, choose M here: the
134 module will be called cpufreq_userspace.
136 For details, take a look at <file:Documentation/cpu-freq/>.
140 config CPU_FREQ_GOV_ONDEMAND
141 tristate "'ondemand' cpufreq policy governor"
142 select CPU_FREQ_GOV_COMMON
144 'ondemand' - This driver adds a dynamic cpufreq policy governor.
145 The governor does a periodic polling and
146 changes frequency based on the CPU utilization.
147 The support for this governor depends on CPU capability to
148 do fast frequency switching (i.e, very low latency frequency
151 To compile this driver as a module, choose M here: the
152 module will be called cpufreq_ondemand.
154 For details, take a look at linux/Documentation/cpu-freq.
158 config CPU_FREQ_GOV_CONSERVATIVE
159 tristate "'conservative' cpufreq governor"
161 select CPU_FREQ_GOV_COMMON
163 'conservative' - this driver is rather similar to the 'ondemand'
164 governor both in its source code and its purpose, the difference is
165 its optimisation for better suitability in a battery powered
166 environment. The frequency is gracefully increased and decreased
167 rather than jumping to 100% when speed is required.
169 If you have a desktop machine then you should really be considering
170 the 'ondemand' governor instead, however if you are using a laptop,
171 PDA or even an AMD64 based computer (due to the unacceptable
172 step-by-step latency issues between the minimum and maximum frequency
173 transitions in the CPU) you will probably want to use this governor.
175 To compile this driver as a module, choose M here: the
176 module will be called cpufreq_conservative.
178 For details, take a look at linux/Documentation/cpu-freq.
182 config GENERIC_CPUFREQ_CPU0
183 tristate "Generic CPU0 cpufreq driver"
184 depends on HAVE_CLK && REGULATOR && OF
187 This adds a generic cpufreq driver for CPU0 frequency management.
188 It supports both uniprocessor (UP) and symmetric multiprocessor (SMP)
189 systems which share clock and voltage across all CPUs.
193 menu "x86 CPU frequency scaling drivers"
195 source "drivers/cpufreq/Kconfig.x86"
198 menu "ARM CPU frequency scaling drivers"
200 source "drivers/cpufreq/Kconfig.arm"
203 menu "AVR32 CPU frequency scaling drivers"
206 config AVR32_AT32AP_CPUFREQ
207 bool "CPU frequency driver for AT32AP"
208 depends on PLATFORM_AT32AP
211 This enables the CPU frequency driver for AT32AP processors.
216 menu "CPUFreq processor drivers"
219 config IA64_ACPI_CPUFREQ
220 tristate "ACPI Processor P-States driver"
221 depends on ACPI_PROCESSOR
223 This driver adds a CPUFreq driver which utilizes the ACPI
224 Processor Performance States.
226 For details, take a look at <file:Documentation/cpu-freq/>.
232 menu "MIPS CPUFreq processor drivers"
235 config LOONGSON2_CPUFREQ
236 tristate "Loongson2 CPUFreq Driver"
238 This option adds a CPUFreq driver for loongson processors which
239 support software configurable cpu frequency.
241 Loongson2F and it's successors support this feature.
243 For details, take a look at <file:Documentation/cpu-freq/>.
249 menu "PowerPC CPU frequency scaling drivers"
250 depends on PPC32 || PPC64
251 source "drivers/cpufreq/Kconfig.powerpc"
254 menu "SPARC CPU frequency scaling drivers"
256 config SPARC_US3_CPUFREQ
257 tristate "UltraSPARC-III CPU Frequency driver"
259 This adds the CPUFreq driver for UltraSPARC-III processors.
261 For details, take a look at <file:Documentation/cpu-freq>.
265 config SPARC_US2E_CPUFREQ
266 tristate "UltraSPARC-IIe CPU Frequency driver"
268 This adds the CPUFreq driver for UltraSPARC-IIe processors.
270 For details, take a look at <file:Documentation/cpu-freq>.
275 menu "SH CPU Frequency scaling"
278 tristate "SuperH CPU Frequency driver"
280 This adds the cpufreq driver for SuperH. Any CPU that supports
281 clock rate rounding through the clock framework can use this
282 driver. While it will make the kernel slightly larger, this is
283 harmless for CPUs that don't support rate rounding. The driver
284 will also generate a notice in the boot log before disabling
285 itself if the CPU in question is not capable of rate rounding.
287 For details, take a look at <file:Documentation/cpu-freq>.