diff options
Diffstat (limited to 'Documentation/admin-guide')
| -rw-r--r-- | Documentation/admin-guide/pm/intel_uncore_frequency_scaling.rst | 57 |
1 files changed, 56 insertions, 1 deletions
diff --git a/Documentation/admin-guide/pm/intel_uncore_frequency_scaling.rst b/Documentation/admin-guide/pm/intel_uncore_frequency_scaling.rst index 09169d935835..5ab3440e6cee 100644 --- a/Documentation/admin-guide/pm/intel_uncore_frequency_scaling.rst +++ b/Documentation/admin-guide/pm/intel_uncore_frequency_scaling.rst @@ -5,7 +5,7 @@ Intel Uncore Frequency Scaling ============================== -:Copyright: |copy| 2022 Intel Corporation +:Copyright: |copy| 2022-2023 Intel Corporation :Author: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> @@ -58,3 +58,58 @@ Each package_*_die_* contains the following attributes: ``current_freq_khz`` This attribute is used to get the current uncore frequency. + +SoCs with TPMI (Topology Aware Register and PM Capsule Interface) +----------------------------------------------------------------- + +An SoC can contain multiple power domains with individual or collection +of mesh partitions. This partition is called fabric cluster. + +Certain type of meshes will need to run at the same frequency, they will +be placed in the same fabric cluster. Benefit of fabric cluster is that it +offers a scalable mechanism to deal with partitioned fabrics in a SoC. + +The current sysfs interface supports controls at package and die level. +This interface is not enough to support more granular control at +fabric cluster level. + +SoCs with the support of TPMI (Topology Aware Register and PM Capsule +Interface), can have multiple power domains. Each power domain can +contain one or more fabric clusters. + +To represent controls at fabric cluster level in addition to the +controls at package and die level (like systems without TPMI +support), sysfs is enhanced. This granular interface is presented in the +sysfs with directories names prefixed with "uncore". For example: +uncore00, uncore01 etc. + +The scope of control is specified by attributes "package_id", "domain_id" +and "fabric_cluster_id" in the directory. + +Attributes in each directory: + +``domain_id`` + This attribute is used to get the power domain id of this instance. + +``fabric_cluster_id`` + This attribute is used to get the fabric cluster id of this instance. + +``package_id`` + This attribute is used to get the package id of this instance. + +The other attributes are same as presented at package_*_die_* level. + +In most of current use cases, the "max_freq_khz" and "min_freq_khz" +is updated at "package_*_die_*" level. This model will be still supported +with the following approach: + +When user uses controls at "package_*_die_*" level, then every fabric +cluster is affected in that package and die. For example: user changes +"max_freq_khz" in the package_00_die_00, then "max_freq_khz" for uncore* +directory with the same package id will be updated. In this case user can +still update "max_freq_khz" at each uncore* level, which is more restrictive. +Similarly, user can update "min_freq_khz" at "package_*_die_*" level +to apply at each uncore* level. + +Support for "current_freq_khz" is available only at each fabric cluster +level (i.e., in uncore* directory). |