mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-24 01:41:39 +00:00
![Randy Dunlap](/assets/img/avatar_default.png)
Correct spelling problems for Documentation/userspace-api/ as reported by codespell. Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: linux-doc@vger.kernel.org Cc: Sean Young <sean@mess.org> Cc: Mauro Carvalho Chehab <mchehab@kernel.org> Cc: linux-media@vger.kernel.org Link: https://lore.kernel.org/r/20230129231053.20863-10-rdunlap@infradead.org Signed-off-by: Jonathan Corbet <corbet@lwn.net>
42 lines
2.2 KiB
ReStructuredText
42 lines
2.2 KiB
ReStructuredText
=====================================================================
|
|
Platform Profile Selection (e.g. /sys/firmware/acpi/platform_profile)
|
|
=====================================================================
|
|
|
|
On modern systems the platform performance, temperature, fan and other
|
|
hardware related characteristics are often dynamically configurable. The
|
|
platform configuration is often automatically adjusted to the current
|
|
conditions by some automatic mechanism (which may very well live outside
|
|
the kernel).
|
|
|
|
These auto platform adjustment mechanisms often can be configured with
|
|
one of several platform profiles, with either a bias towards low power
|
|
operation or towards performance.
|
|
|
|
The purpose of the platform_profile attribute is to offer a generic sysfs
|
|
API for selecting the platform profile of these automatic mechanisms.
|
|
|
|
Note that this API is only for selecting the platform profile, it is
|
|
NOT a goal of this API to allow monitoring the resulting performance
|
|
characteristics. Monitoring performance is best done with device/vendor
|
|
specific tools such as e.g. turbostat.
|
|
|
|
Specifically when selecting a high performance profile the actual achieved
|
|
performance may be limited by various factors such as: the heat generated
|
|
by other components, room temperature, free air flow at the bottom of a
|
|
laptop, etc. It is explicitly NOT a goal of this API to let userspace know
|
|
about any sub-optimal conditions which are impeding reaching the requested
|
|
performance level.
|
|
|
|
Since numbers on their own cannot represent the multiple variables that a
|
|
profile will adjust (power consumption, heat generation, etc) this API
|
|
uses strings to describe the various profiles. To make sure that userspace
|
|
gets a consistent experience the sysfs-platform_profile ABI document defines
|
|
a fixed set of profile names. Drivers *must* map their internal profile
|
|
representation onto this fixed set.
|
|
|
|
If there is no good match when mapping then a new profile name may be
|
|
added. Drivers which wish to introduce new profile names must:
|
|
|
|
1. Explain why the existing profile names cannot be used.
|
|
2. Add the new profile name, along with a clear description of the
|
|
expected behaviour, to the sysfs-platform_profile ABI documentation.
|