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 responsibility 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 68config ARM_EXYNOS4_BUS_DEVFREQ 69 bool "ARM Exynos4210/4212/4412 Memory Bus DEVFREQ Driver" 70 depends on CPU_EXYNOS4210 || CPU_EXYNOS4212 || CPU_EXYNOS4412 71 select ARCH_HAS_OPP 72 select DEVFREQ_GOV_SIMPLE_ONDEMAND 73 help 74 This adds the DEVFREQ driver for Exynos4210 memory bus (vdd_int) 75 and Exynos4212/4412 memory interface and bus (vdd_mif + vdd_int). 76 It reads PPMU counters of memory controllers and adjusts 77 the operating frequencies and voltages with OPP support. 78 To operate with optimal voltages, ASV support is required 79 (CONFIG_EXYNOS_ASV). 80 81endif # PM_DEVFREQ 82