Linux v5.2.1 - devfreq
# SPDX-License-Identifier: GPL-2.0-only
bool "Generic Dynamic Voltage and Frequency Scaling (DVFS) support"
A device may have a list of frequencies and voltages available.
devfreq, a generic DVFS framework can be registered for a device
in order to let the governor provided to devfreq choose an
operating frequency based on the device driver's policy.
Each device may have its own governor and policy. Devfreq can
reevaluate the device state periodically and/or based on the
notification to "nb", a notifier block, of devfreq.
Like some CPUs with CPUfreq, a device may have multiple clocks.
However, because the clock frequencies of a single device are
determined by the single device's state, an instance of devfreq
is attached to a single device and returns a "representative"
clock frequency of the device, which is also attached
to a device by 1-to-1. The device registering devfreq takes the
responsibility to "interpret" the representative frequency and
to set its every clock accordingly with the "target" callback
given to devfreq.
When OPP is used with the devfreq device, it is recommended to
register devfreq's nb to the OPP's notifier head. If OPP is
used with the devfreq device, you may use OPP helper
functions defined in devfreq.h.
comment "DEVFREQ Governors"
tristate "Simple Ondemand"
Chooses frequency based on the recent load on the device. Works
similar as ONDEMAND governor of CPUFREQ does. A device with
Simple-Ondemand should be able to provide busy/total counter
values that imply the usage rate. A device may provide tuned
values to the governor with data field at devfreq_add_device().
Sets the frequency at the maximum available frequency.
This governor always returns UINT_MAX as frequency so that
the DEVFREQ framework returns the highest frequency available
at any time.
Sets the frequency at the minimum available frequency.
This governor always returns 0 as frequency so that
the DEVFREQ framework returns the lowest frequency available
at any time.
Sets the frequency at the user specified one.
This governor returns the user configured frequency if there
has been an input to /sys/devices/.../power/devfreq_set_freq.
Otherwise, the governor does not change the frequency
given at the initialization.
Sets the frequency based on the frequency of its parent devfreq
device. This governor does not change the frequency by itself
through sysfs entries. The passive governor recommends that
devfreq device uses the OPP table to get the frequency/voltage.
comment "DEVFREQ Drivers"
tristate "ARM EXYNOS Generic Memory Bus DEVFREQ Driver"
depends on ARCH_EXYNOS || COMPILE_TEST
This adds the common DEVFREQ driver for Exynos Memory bus. Exynos
Memory bus has one more group of memory bus (e.g, MIF and INT block).
Each memory bus group could contain many memoby bus block. It reads
PPMU counters of memory controllers by using DEVFREQ-event device
and adjusts the operating frequencies and voltages with OPP support.
This does not yet operate with optimal voltages.
tristate "Tegra DEVFREQ Driver"
depends on ARCH_TEGRA_124_SOC
This adds the DEVFREQ driver for the Tegra family of SoCs.
It reads ACTMON counters of memory controllers and adjusts the
operating frequencies and voltages with OPP support.
tristate "ARM RK3399 DMC DEVFREQ Driver"
depends on ARCH_ROCKCHIP
This adds the DEVFREQ driver for the RK3399 DMC(Dynamic Memory Controller).
It sets the frequency for the memory controller and reads the usage counts
endif # PM_DEVFREQ