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Linus Torvalds1da177e2005-04-16 15:20:36 -07001config 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 def_tristate m
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
42config CPU_FREQ_STAT_DETAILS
43 bool "CPU frequency translation statistics details"
44 depends on CPU_FREQ_STAT
45 help
46 This will show detail CPU frequency translation table in sysfs file
47 system
48
Dave Jones331001082005-05-31 19:03:44 -070049# Note that it is not currently possible to set the other governors (such as ondemand)
50# as the default, since if they fail to initialise, cpufreq will be
51# left in an undefined state.
52
Linus Torvalds1da177e2005-04-16 15:20:36 -070053choice
54 prompt "Default CPUFreq governor"
55 default CPU_FREQ_DEFAULT_GOV_USERSPACE if CPU_FREQ_SA1100 || CPU_FREQ_SA1110
56 default CPU_FREQ_DEFAULT_GOV_PERFORMANCE
57 help
58 This option sets which CPUFreq governor shall be loaded at
59 startup. If in doubt, select 'performance'.
60
61config CPU_FREQ_DEFAULT_GOV_PERFORMANCE
62 bool "performance"
63 select CPU_FREQ_GOV_PERFORMANCE
64 help
65 Use the CPUFreq governor 'performance' as default. This sets
66 the frequency statically to the highest frequency supported by
67 the CPU.
68
69config CPU_FREQ_DEFAULT_GOV_USERSPACE
70 bool "userspace"
71 select CPU_FREQ_GOV_USERSPACE
72 help
73 Use the CPUFreq governor 'userspace' as default. This allows
74 you to set the CPU frequency manually or when an userspace
75 program shall be able to set the CPU dynamically without having
76 to enable the userspace governor manually.
77
78endchoice
79
80config CPU_FREQ_GOV_PERFORMANCE
81 tristate "'performance' governor"
82 help
83 This cpufreq governor sets the frequency statically to the
84 highest available CPU frequency.
85
86 If in doubt, say Y.
87
88config CPU_FREQ_GOV_POWERSAVE
89 tristate "'powersave' governor"
90 help
91 This cpufreq governor sets the frequency statically to the
92 lowest available CPU frequency.
93
94 If in doubt, say Y.
95
96config CPU_FREQ_GOV_USERSPACE
97 tristate "'userspace' governor for userspace frequency scaling"
98 help
99 Enable this cpufreq governor when you either want to set the
100 CPU frequency manually or when an userspace program shall
101 be able to set the CPU dynamically, like on LART
102 <http://www.lart.tudelft.nl/>
103
104 For details, take a look at <file:Documentation/cpu-freq/>.
105
106 If in doubt, say Y.
107
108config CPU_FREQ_GOV_ONDEMAND
109 tristate "'ondemand' cpufreq policy governor"
110 help
111 'ondemand' - This driver adds a dynamic cpufreq policy governor.
112 The governor does a periodic polling and
113 changes frequency based on the CPU utilization.
114 The support for this governor depends on CPU capability to
115 do fast frequency switching (i.e, very low latency frequency
116 transitions).
117
118 For details, take a look at linux/Documentation/cpu-freq.
119
120 If in doubt, say N.
121
Dave Jonesb9170832005-05-31 19:03:47 -0700122config CPU_FREQ_GOV_CONSERVATIVE
123 tristate "'conservative' cpufreq governor"
124 depends on CPU_FREQ
125 help
126 'conservative' - this driver is rather similar to the 'ondemand'
127 governor both in its source code and its purpose, the difference is
128 its optimisation for better suitability in a battery powered
129 environment. The frequency is gracefully increased and decreased
130 rather than jumping to 100% when speed is required.
131
132 If you have a desktop machine then you should really be considering
133 the 'ondemand' governor instead, however if you are using a laptop,
134 PDA or even an AMD64 based computer (due to the unacceptable
135 step-by-step latency issues between the minimum and maximum frequency
136 transitions in the CPU) you will probably want to use this governor.
137
138 For details, take a look at linux/Documentation/cpu-freq.
139
140 If in doubt, say N.
141
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142endif # CPU_FREQ