summaryrefslogtreecommitdiffstats
path: root/Documentation/admin-guide
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/admin-guide')
-rw-r--r--Documentation/admin-guide/pm/intel_uncore_frequency_scaling.rst57
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).