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>.
21 config CPU_FREQ_GOV_ATTR_SET
24 config CPU_FREQ_GOV_COMMON
25 select CPU_FREQ_GOV_ATTR_SET
29 config CPU_FREQ_BOOST_SW
34 tristate "CPU frequency translation statistics"
37 This driver exports CPU frequency statistics information through sysfs
40 To compile this driver as a module, choose M here: the
41 module will be called cpufreq_stats.
45 config CPU_FREQ_STAT_DETAILS
46 bool "CPU frequency translation statistics details"
47 depends on CPU_FREQ_STAT
49 This will show detail CPU frequency translation table in sysfs file
55 prompt "Default CPUFreq governor"
56 default CPU_FREQ_DEFAULT_GOV_USERSPACE if ARM_SA1100_CPUFREQ || ARM_SA1110_CPUFREQ
57 default CPU_FREQ_DEFAULT_GOV_PERFORMANCE
59 This option sets which CPUFreq governor shall be loaded at
60 startup. If in doubt, select 'performance'.
62 config CPU_FREQ_DEFAULT_GOV_PERFORMANCE
64 select CPU_FREQ_GOV_PERFORMANCE
66 Use the CPUFreq governor 'performance' as default. This sets
67 the frequency statically to the highest frequency supported by
70 config CPU_FREQ_DEFAULT_GOV_POWERSAVE
72 select CPU_FREQ_GOV_POWERSAVE
74 Use the CPUFreq governor 'powersave' as default. This sets
75 the frequency statically to the lowest frequency supported by
78 config CPU_FREQ_DEFAULT_GOV_USERSPACE
80 select CPU_FREQ_GOV_USERSPACE
82 Use the CPUFreq governor 'userspace' as default. This allows
83 you to set the CPU frequency manually or when a userspace
84 program shall be able to set the CPU dynamically without having
85 to enable the userspace governor manually.
87 config CPU_FREQ_DEFAULT_GOV_ONDEMAND
89 select CPU_FREQ_GOV_ONDEMAND
90 select CPU_FREQ_GOV_PERFORMANCE
92 Use the CPUFreq governor 'ondemand' as default. This allows
93 you to get a full dynamic frequency capable system by simply
94 loading your cpufreq low-level hardware driver.
95 Be aware that not all cpufreq drivers support the ondemand
96 governor. If unsure have a look at the help section of the
97 driver. Fallback governor will be the performance governor.
99 config CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
101 select CPU_FREQ_GOV_CONSERVATIVE
102 select CPU_FREQ_GOV_PERFORMANCE
104 Use the CPUFreq governor 'conservative' as default. This allows
105 you to get a full dynamic frequency capable system by simply
106 loading your cpufreq low-level hardware driver.
107 Be aware that not all cpufreq drivers support the conservative
108 governor. If unsure have a look at the help section of the
109 driver. Fallback governor will be the performance governor.
112 config CPU_FREQ_GOV_PERFORMANCE
113 tristate "'performance' governor"
115 This cpufreq governor sets the frequency statically to the
116 highest available CPU frequency.
118 To compile this driver as a module, choose M here: the
119 module will be called cpufreq_performance.
123 config CPU_FREQ_GOV_POWERSAVE
124 tristate "'powersave' governor"
126 This cpufreq governor sets the frequency statically to the
127 lowest available CPU frequency.
129 To compile this driver as a module, choose M here: the
130 module will be called cpufreq_powersave.
134 config CPU_FREQ_GOV_USERSPACE
135 tristate "'userspace' governor for userspace frequency scaling"
137 Enable this cpufreq governor when you either want to set the
138 CPU frequency manually or when a userspace program shall
139 be able to set the CPU dynamically, like on LART
140 <http://www.lartmaker.nl/>.
142 To compile this driver as a module, choose M here: the
143 module will be called cpufreq_userspace.
145 For details, take a look at <file:Documentation/cpu-freq/>.
149 config CPU_FREQ_GOV_ONDEMAND
150 tristate "'ondemand' cpufreq policy governor"
151 select CPU_FREQ_GOV_COMMON
153 'ondemand' - This driver adds a dynamic cpufreq policy governor.
154 The governor does a periodic polling and
155 changes frequency based on the CPU utilization.
156 The support for this governor depends on CPU capability to
157 do fast frequency switching (i.e, very low latency frequency
160 To compile this driver as a module, choose M here: the
161 module will be called cpufreq_ondemand.
163 For details, take a look at linux/Documentation/cpu-freq.
167 config CPU_FREQ_GOV_CONSERVATIVE
168 tristate "'conservative' cpufreq governor"
170 select CPU_FREQ_GOV_COMMON
172 'conservative' - this driver is rather similar to the 'ondemand'
173 governor both in its source code and its purpose, the difference is
174 its optimisation for better suitability in a battery powered
175 environment. The frequency is gracefully increased and decreased
176 rather than jumping to 100% when speed is required.
178 If you have a desktop machine then you should really be considering
179 the 'ondemand' governor instead, however if you are using a laptop,
180 PDA or even an AMD64 based computer (due to the unacceptable
181 step-by-step latency issues between the minimum and maximum frequency
182 transitions in the CPU) you will probably want to use this governor.
184 To compile this driver as a module, choose M here: the
185 module will be called cpufreq_conservative.
187 For details, take a look at linux/Documentation/cpu-freq.
191 comment "CPU frequency scaling drivers"
194 tristate "Generic DT based cpufreq driver"
195 depends on HAVE_CLK && OF
196 # if CPU_THERMAL is on and THERMAL=m, CPUFREQ_DT cannot be =y:
197 depends on !CPU_THERMAL || THERMAL
200 This adds a generic DT based cpufreq driver for frequency management.
201 It supports both uniprocessor (UP) and symmetric multiprocessor (SMP)
202 systems which share clock and voltage across all CPUs.
207 source "drivers/cpufreq/Kconfig.x86"
211 source "drivers/cpufreq/Kconfig.arm"
215 source "drivers/cpufreq/Kconfig.powerpc"
219 config AVR32_AT32AP_CPUFREQ
220 bool "CPU frequency driver for AT32AP"
221 depends on PLATFORM_AT32AP
224 This enables the CPU frequency driver for AT32AP processors.
229 config IA64_ACPI_CPUFREQ
230 tristate "ACPI Processor P-States driver"
231 depends on ACPI_PROCESSOR
233 This driver adds a CPUFreq driver which utilizes the ACPI
234 Processor Performance States.
236 For details, take a look at <file:Documentation/cpu-freq/>.
242 config LOONGSON2_CPUFREQ
243 tristate "Loongson2 CPUFreq Driver"
245 This option adds a CPUFreq driver for loongson processors which
246 support software configurable cpu frequency.
248 Loongson2F and it's successors support this feature.
250 For details, take a look at <file:Documentation/cpu-freq/>.
254 config LOONGSON1_CPUFREQ
255 tristate "Loongson1 CPUFreq Driver"
257 This option adds a CPUFreq driver for loongson1 processors which
258 support software configurable cpu frequency.
260 For details, take a look at <file:Documentation/cpu-freq/>.
266 config SPARC_US3_CPUFREQ
267 tristate "UltraSPARC-III CPU Frequency driver"
269 This adds the CPUFreq driver for UltraSPARC-III processors.
271 For details, take a look at <file:Documentation/cpu-freq>.
275 config SPARC_US2E_CPUFREQ
276 tristate "UltraSPARC-IIe CPU Frequency driver"
278 This adds the CPUFreq driver for UltraSPARC-IIe processors.
280 For details, take a look at <file:Documentation/cpu-freq>.
287 tristate "SuperH CPU Frequency driver"
289 This adds the cpufreq driver for SuperH. Any CPU that supports
290 clock rate rounding through the clock framework can use this
291 driver. While it will make the kernel slightly larger, this is
292 harmless for CPUs that don't support rate rounding. The driver
293 will also generate a notice in the boot log before disabling
294 itself if the CPU in question is not capable of rate rounding.
296 For details, take a look at <file:Documentation/cpu-freq>.
302 tristate "CPU frequency scaling driver for Freescale QorIQ SoCs"
303 depends on OF && COMMON_CLK && (PPC_E500MC || ARM)
304 depends on !CPU_THERMAL || THERMAL
307 This adds the CPUFreq driver support for Freescale QorIQ SoCs
308 which are capable of changing the CPU's frequency dynamically.