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1menuconfig PM_DEVFREQ
2 bool "Generic Dynamic Voltage and Frequency Scaling (DVFS) support"
3 help
4 A device may have a list of frequencies and voltages available.
5 devfreq, a generic DVFS framework can be registered for a device
6 in order to let the governor provided to devfreq choose an
7 operating frequency based on the device driver's policy.
8
9 Each device may have its own governor and policy. Devfreq can
10 reevaluate the device state periodically and/or based on the
11 notification to "nb", a notifier block, of devfreq.
12
13 Like some CPUs with CPUfreq, a device may have multiple clocks.
14 However, because the clock frequencies of a single device are
15 determined by the single device's state, an instance of devfreq
16 is attached to a single device and returns a "representative"
17 clock frequency of the device, which is also attached
18 to a device by 1-to-1. The device registering devfreq takes the
19 responsiblity to "interpret" the representative frequency and
20 to set its every clock accordingly with the "target" callback
21 given to devfreq.
22
23 When OPP is used with the devfreq device, it is recommended to
24 register devfreq's nb to the OPP's notifier head. If OPP is
25 used with the devfreq device, you may use OPP helper
26 functions defined in devfreq.h.
27
28if PM_DEVFREQ
29
30comment "DEVFREQ Governors"
31
32config DEVFREQ_GOV_SIMPLE_ONDEMAND
33 bool "Simple Ondemand"
34 help
35 Chooses frequency based on the recent load on the device. Works
36 similar as ONDEMAND governor of CPUFREQ does. A device with
37 Simple-Ondemand should be able to provide busy/total counter
38 values that imply the usage rate. A device may provide tuned
39 values to the governor with data field at devfreq_add_device().
40
41config DEVFREQ_GOV_PERFORMANCE
42 bool "Performance"
43 help
44 Sets the frequency at the maximum available frequency.
45 This governor always returns UINT_MAX as frequency so that
46 the DEVFREQ framework returns the highest frequency available
47 at any time.
48
49config DEVFREQ_GOV_POWERSAVE
50 bool "Powersave"
51 help
52 Sets the frequency at the minimum available frequency.
53 This governor always returns 0 as frequency so that
54 the DEVFREQ framework returns the lowest frequency available
55 at any time.
56
57config DEVFREQ_GOV_USERSPACE
58 bool "Userspace"
59 help
60 Sets the frequency at the user specified one.
61 This governor returns the user configured frequency if there
62 has been an input to /sys/devices/.../power/devfreq_set_freq.
63 Otherwise, the governor does not change the frequnecy
64 given at the initialization.
65
66comment "DEVFREQ Drivers"
67
68endif # PM_DEVFREQ