From: Hans de Goede <hdegoede@xxxxxxxxxx> On modern systems the platform performance, temperature, fan and other hardware related characteristics are often dynamically configurable. The profile is often automatically adjusted to the load by somei 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 consumption or towards performance (and higher power consumption and thermals). Introduce a new platform_profile sysfs API which offers a generic API for selecting the performance-profile of these automatic-mechanisms. Co-developed-by: Mark Pearson <markpearson@xxxxxxxxxx> Signed-off-by: Mark Pearson <markpearson@xxxxxxxxxx> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> --- .../ABI/testing/sysfs-platform_profile | 85 +++++++++++++++++++ 1 file changed, 85 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-platform_profile diff --git a/Documentation/ABI/testing/sysfs-platform_profile b/Documentation/ABI/testing/sysfs-platform_profile new file mode 100644 index 000000000000..37cb6275946c --- /dev/null +++ b/Documentation/ABI/testing/sysfs-platform_profile @@ -0,0 +1,85 @@ +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 +profile is often automatically adjusted to the load 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 +consumption or towards performance (and higher power consumption and +thermals). + +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 are a rather meaningless way to describe platform-profiles +this API uses strings to describe the various profiles. To make sure that +userspace gets a consistent experience when using this API this API +document defines a fixed set of profile-names. Drivers *must* map their +internal profile representation/names onto this fixed set. + +If for some reason 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. Have very good reasons to do so. +2. Add the new profile-name to this document, so that future drivers which also + have a similar problem can use the same new. Usually new profile-names will + be added to the "extra profile-names" section of this document. But in some + cases the set of standard profile-names may be extended. + +What: /sys/firmware/acpi/platform_profile_choices +Date: October 2020 +Contact: Hans de Goede <hdegoede@xxxxxxxxxx> +Description: + Reading this file gives a space separated list of profiles + supported for this device. + + Drivers must use the following standard profile-names whenever + possible: + + low-power: Emphasises low power consumption + quiet: Offers quieter operation (lower fan + speed but with higher performance and + temperatures then seen in low-power + balanced: Balance between low power consumption + and performance + performance: Emphasises performance (and may lead to + higher temperatures and fan speeds) + + Userspace may expect drivers to offer at least several of these + standard profile-names! If none of the above are a good match + for some of the drivers profiles, then drivers may use one of + these extra profile-names: + <reserved for future use> + +What: /sys/firmware/acpi/platform_profile +Date: October 2020 +Contact: Hans de Goede <hdegoede@xxxxxxxxxx> +Description: + Reading this file gives the current selected profile for this + device. Writing this file with one of the strings from + available_profiles changes the profile to the new value. + + Reading this file may also return "custom". This is intended for + drivers which have and export multiple knobs. Such drivers may + very well still want to offer a set of profiles for easy of use + and to be able to offer a consistent standard API (this API) to + userspace for configuring their performance. The "custom" value + is intended for when ai user has directly configured the knobs + (through e.g. some advanced control-panel for a GPU) and the + knob values do not match any of the presets represented by the + platform-profiles. In this case writing this file will + override the modifications and restore the selected presets. + -- 2.28.0
