| MyungJoo Ham | a3c98b8 | 2011-10-02 00:19:15 +0200 | [diff] [blame] | 1 | menuconfig PM_DEVFREQ |
| 2 | bool "Generic Dynamic Voltage and Frequency Scaling (DVFS) support" |
| MyungJoo Ham | a3c98b8 | 2011-10-02 00:19:15 +0200 | [diff] [blame] | 3 | help |
| MyungJoo Ham | 6c81f90 | 2011-11-14 23:31:35 +0100 | [diff] [blame] | 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. |
| MyungJoo Ham | a3c98b8 | 2011-10-02 00:19:15 +0200 | [diff] [blame] | 8 | |
| MyungJoo Ham | 6c81f90 | 2011-11-14 23:31:35 +0100 | [diff] [blame] | 9 | Each device may have its own governor and policy. Devfreq can |
| MyungJoo Ham | a3c98b8 | 2011-10-02 00:19:15 +0200 | [diff] [blame] | 10 | reevaluate the device state periodically and/or based on the |
| MyungJoo Ham | 6c81f90 | 2011-11-14 23:31:35 +0100 | [diff] [blame] | 11 | notification to "nb", a notifier block, of devfreq. |
| MyungJoo Ham | a3c98b8 | 2011-10-02 00:19:15 +0200 | [diff] [blame] | 12 | |
| MyungJoo Ham | 6c81f90 | 2011-11-14 23:31:35 +0100 | [diff] [blame] | 13 | Like some CPUs with CPUfreq, a device may have multiple clocks. |
| MyungJoo Ham | a3c98b8 | 2011-10-02 00:19:15 +0200 | [diff] [blame] | 14 | However, because the clock frequencies of a single device are |
| MyungJoo Ham | 6c81f90 | 2011-11-14 23:31:35 +0100 | [diff] [blame] | 15 | determined by the single device's state, an instance of devfreq |
| MyungJoo Ham | a3c98b8 | 2011-10-02 00:19:15 +0200 | [diff] [blame] | 16 | is attached to a single device and returns a "representative" |
| MyungJoo Ham | 6c81f90 | 2011-11-14 23:31:35 +0100 | [diff] [blame] | 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 |
| MyungJoo Ham | a3c98b8 | 2011-10-02 00:19:15 +0200 | [diff] [blame] | 20 | to set its every clock accordingly with the "target" callback |
| MyungJoo Ham | 6c81f90 | 2011-11-14 23:31:35 +0100 | [diff] [blame] | 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. |
| MyungJoo Ham | a3c98b8 | 2011-10-02 00:19:15 +0200 | [diff] [blame] | 27 | |
| 28 | if PM_DEVFREQ |
| 29 | |
| MyungJoo Ham | ce26c5b | 2011-10-02 00:19:34 +0200 | [diff] [blame] | 30 | comment "DEVFREQ Governors" |
| 31 | |
| 32 | config 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 | |
| 41 | config 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 | |
| 49 | config 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 | |
| 57 | config 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 | |
| MyungJoo Ham | a3c98b8 | 2011-10-02 00:19:15 +0200 | [diff] [blame] | 66 | comment "DEVFREQ Drivers" |
| 67 | |
| 68 | endif # PM_DEVFREQ |