Root/drivers/cpufreq/Kconfig

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      For details, take a look at <file:Documentation/cpu-freq>.
13
14      If in doubt, say N.
15
16if CPU_FREQ
17
18config CPU_FREQ_TABLE
19    tristate
20
21config CPU_FREQ_DEBUG
22    bool "Enable CPUfreq debugging"
23    help
24      Say Y here to enable CPUfreq subsystem (including drivers)
25      debugging. You will need to activate it via the kernel
26      command line by passing
27         cpufreq.debug=<value>
28
29      To get <value>, add
30           1 to activate CPUfreq core debugging,
31           2 to activate CPUfreq drivers debugging, and
32           4 to activate CPUfreq governor debugging
33
34config CPU_FREQ_STAT
35    tristate "CPU frequency translation statistics"
36    select CPU_FREQ_TABLE
37    default y
38    help
39      This driver exports CPU frequency statistics information through sysfs
40      file system.
41
42      To compile this driver as a module, choose M here: the
43      module will be called cpufreq_stats.
44
45      If in doubt, say N.
46
47config CPU_FREQ_STAT_DETAILS
48    bool "CPU frequency translation statistics details"
49    depends on CPU_FREQ_STAT
50    help
51      This will show detail CPU frequency translation table in sysfs file
52      system.
53
54      If in doubt, say N.
55
56choice
57    prompt "Default CPUFreq governor"
58    default CPU_FREQ_DEFAULT_GOV_USERSPACE if CPU_FREQ_SA1100 || CPU_FREQ_SA1110
59    default CPU_FREQ_DEFAULT_GOV_PERFORMANCE
60    help
61      This option sets which CPUFreq governor shall be loaded at
62      startup. If in doubt, select 'performance'.
63
64config CPU_FREQ_DEFAULT_GOV_PERFORMANCE
65    bool "performance"
66    select CPU_FREQ_GOV_PERFORMANCE
67    help
68      Use the CPUFreq governor 'performance' as default. This sets
69      the frequency statically to the highest frequency supported by
70      the CPU.
71
72config CPU_FREQ_DEFAULT_GOV_POWERSAVE
73    bool "powersave"
74    depends on EMBEDDED
75    select CPU_FREQ_GOV_POWERSAVE
76    help
77      Use the CPUFreq governor 'powersave' as default. This sets
78      the frequency statically to the lowest frequency supported by
79      the CPU.
80
81config CPU_FREQ_DEFAULT_GOV_USERSPACE
82    bool "userspace"
83    select CPU_FREQ_GOV_USERSPACE
84    help
85      Use the CPUFreq governor 'userspace' as default. This allows
86      you to set the CPU frequency manually or when a userspace
87      program shall be able to set the CPU dynamically without having
88      to enable the userspace governor manually.
89
90config CPU_FREQ_DEFAULT_GOV_ONDEMAND
91    bool "ondemand"
92    select CPU_FREQ_GOV_ONDEMAND
93    select CPU_FREQ_GOV_PERFORMANCE
94    help
95      Use the CPUFreq governor 'ondemand' 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 ondemand
99      governor. If unsure have a look at the help section of the
100      driver. Fallback governor will be the performance governor.
101
102config CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
103    bool "conservative"
104    select CPU_FREQ_GOV_CONSERVATIVE
105    select CPU_FREQ_GOV_PERFORMANCE
106    help
107      Use the CPUFreq governor 'conservative' as default. This allows
108      you to get a full dynamic frequency capable system by simply
109      loading your cpufreq low-level hardware driver.
110      Be aware that not all cpufreq drivers support the conservative
111      governor. If unsure have a look at the help section of the
112      driver. Fallback governor will be the performance governor.
113endchoice
114
115config CPU_FREQ_GOV_PERFORMANCE
116    tristate "'performance' governor"
117    help
118      This cpufreq governor sets the frequency statically to the
119      highest available CPU frequency.
120
121      To compile this driver as a module, choose M here: the
122      module will be called cpufreq_performance.
123
124      If in doubt, say Y.
125
126config CPU_FREQ_GOV_POWERSAVE
127    tristate "'powersave' governor"
128    help
129      This cpufreq governor sets the frequency statically to the
130      lowest available CPU frequency.
131
132      To compile this driver as a module, choose M here: the
133      module will be called cpufreq_powersave.
134
135      If in doubt, say Y.
136
137config CPU_FREQ_GOV_USERSPACE
138    tristate "'userspace' governor for userspace frequency scaling"
139    help
140      Enable this cpufreq governor when you either want to set the
141      CPU frequency manually or when a userspace program shall
142      be able to set the CPU dynamically, like on LART
143      <http://www.lartmaker.nl/>.
144
145      To compile this driver as a module, choose M here: the
146      module will be called cpufreq_userspace.
147
148      For details, take a look at <file:Documentation/cpu-freq/>.
149
150      If in doubt, say Y.
151
152config CPU_FREQ_GOV_ONDEMAND
153    tristate "'ondemand' cpufreq policy governor"
154    select CPU_FREQ_TABLE
155    help
156      'ondemand' - This driver adds a dynamic cpufreq policy governor.
157      The governor does a periodic polling and
158      changes frequency based on the CPU utilization.
159      The support for this governor depends on CPU capability to
160      do fast frequency switching (i.e, very low latency frequency
161      transitions).
162
163      To compile this driver as a module, choose M here: the
164      module will be called cpufreq_ondemand.
165
166      For details, take a look at linux/Documentation/cpu-freq.
167
168      If in doubt, say N.
169
170config CPU_FREQ_GOV_CONSERVATIVE
171    tristate "'conservative' cpufreq governor"
172    depends on CPU_FREQ
173    help
174      'conservative' - this driver is rather similar to the 'ondemand'
175      governor both in its source code and its purpose, the difference is
176      its optimisation for better suitability in a battery powered
177      environment. The frequency is gracefully increased and decreased
178      rather than jumping to 100% when speed is required.
179
180      If you have a desktop machine then you should really be considering
181      the 'ondemand' governor instead, however if you are using a laptop,
182      PDA or even an AMD64 based computer (due to the unacceptable
183      step-by-step latency issues between the minimum and maximum frequency
184      transitions in the CPU) you will probably want to use this governor.
185
186      To compile this driver as a module, choose M here: the
187      module will be called cpufreq_conservative.
188
189      For details, take a look at linux/Documentation/cpu-freq.
190
191      If in doubt, say N.
192
193endif # CPU_FREQ
194

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