ffa5096a7c
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: Wyes Karny <wyes.karny@amd.com> Signed-off-by: Perry Yuan <Perry.Yuan@amd.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> |
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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.