Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
Perry Yuan
authored
Add EPP driver support for AMD SoCs which support a dedicated MSR for CPPC. EPP is used by the DPM controller to configure the frequency that a core operates at during short periods of activity. The SoC EPP targets are configured on a scale from 0 to 255 where 0 represents maximum performance and 255 represents maximum efficiency. The amd-pstate driver exports profile string names to userspace that are tied to specific EPP values. The balance_performance string (0x80) provides the best balance for efficiency versus power on most systems, but users can choose other strings to meet their needs as well. $ cat /sys/devices/system/cpu/cpufreq/policy0/energy_performance_available_preferences default performance balance_performance balance_power power $ cat /sys/devices/system/cpu/cpufreq/policy0/energy_performance_preference balance_performance To enable the driver,it needs to add `amd_pstate=active` to kernel command line and kernel will load the active mode epp driver Acked-by:Huang Rui <ray.huang@amd.com> Reviewed-by:
Mario Limonciello <Mario.Limonciello@amd.com> Reviewed-by:
Wyes Karny <wyes.karny@amd.com> Tested-by:
Perry Yuan <Perry.Yuan@amd.com> Signed-off-by:
Rafael J. Wysocki <rafael.j.wysocki@intel.com>