linux-kernel - [Patch 4/5] Documentation: ACPI: add autonomous mode ctrls info in cppc

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Message-ID: <20250211103737.447704-5-sumitg@nvidia.com>
Date: Tue, 11 Feb 2025 16:07:36 +0530
From: Sumit Gupta <sumitg@...dia.com>
To: <rafael@...nel.org>, <viresh.kumar@...aro.org>, <lenb@...nel.org>,
	<robert.moore@...el.com>, <corbet@....net>, <linux-pm@...r.kernel.org>,
	<linux-acpi@...r.kernel.org>, <linux-doc@...r.kernel.org>,
	<acpica-devel@...ts.linux.dev>, <linux-kernel@...r.kernel.org>
CC: <linux-tegra@...r.kernel.org>, <treding@...dia.com>,
	<jonathanh@...dia.com>, <sashal@...dia.com>, <vsethi@...dia.com>,
	<ksitaraman@...dia.com>, <sanjayc@...dia.com>, <bbasu@...dia.com>,
	<sumitg@...dia.com>
Subject: [Patch 4/5] Documentation: ACPI: add autonomous mode ctrls info in cppc_sysfs.txt

Add information about the CPC registers used during Autonomous
Performance Level Selection mode. Also, add information about other
regsiters like Guaranteed performance and Performance limited.

Signed-off-by: Sumit Gupta <sumitg@...dia.com>
---
 Documentation/admin-guide/acpi/cppc_sysfs.rst | 28 +++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/Documentation/admin-guide/acpi/cppc_sysfs.rst b/Documentation/admin-guide/acpi/cppc_sysfs.rst
index 36981c667823..ff3f48d95bb7 100644
--- a/Documentation/admin-guide/acpi/cppc_sysfs.rst
+++ b/Documentation/admin-guide/acpi/cppc_sysfs.rst
@@ -27,22 +27,33 @@ for each cpu X::
   $ ls -lR  /sys/devices/system/cpu/cpu0/acpi_cppc/
   /sys/devices/system/cpu/cpu0/acpi_cppc/:
   total 0
+  -r--r--r-- 1 root root 65536 Mar  5 19:38 auto_activity_window
+  -rw-r--r-- 1 root root 65536 Mar  5 19:38 auto_sel
+  -rw-r--r-- 1 root root 65536 Mar  5 19:38 energy_perf
   -r--r--r-- 1 root root 65536 Mar  5 19:38 feedback_ctrs
+  -r--r--r-- 1 root root 65536 Mar  5 19:38 guaranteed_perf
   -r--r--r-- 1 root root 65536 Mar  5 19:38 highest_perf
   -r--r--r-- 1 root root 65536 Mar  5 19:38 lowest_freq
   -r--r--r-- 1 root root 65536 Mar  5 19:38 lowest_nonlinear_perf
   -r--r--r-- 1 root root 65536 Mar  5 19:38 lowest_perf
+  -rw-r--r-- 1 root root 65536 Mar  5 19:38 max_perf
+  -rw-r--r-- 1 root root 65536 Mar  5 19:38 min_perf
   -r--r--r-- 1 root root 65536 Mar  5 19:38 nominal_freq
   -r--r--r-- 1 root root 65536 Mar  5 19:38 nominal_perf
+  -r--r--r-- 1 root root 65536 Mar  5 19:38 per_limited
   -r--r--r-- 1 root root 65536 Mar  5 19:38 reference_perf
   -r--r--r-- 1 root root 65536 Mar  5 19:38 wraparound_time
 
+Performance Capabilities / Thresholds:
 * highest_perf : Highest performance of this processor (abstract scale).
 * nominal_perf : Highest sustained performance of this processor
   (abstract scale).
 * lowest_nonlinear_perf : Lowest performance of this processor with nonlinear
   power savings (abstract scale).
 * lowest_perf : Lowest performance of this processor (abstract scale).
+* guaranteed_perf : Current maximum sustained performance level of a processor,
+  taking into account all known external constraints. All processors are expected
+  to be able to sustain their guaranteed performance levels simultaneously.
 
 * lowest_freq : CPU frequency corresponding to lowest_perf (in MHz).
 * nominal_freq : CPU frequency corresponding to nominal_perf (in MHz).
@@ -50,6 +61,7 @@ for each cpu X::
   frequency instead of abstract scale. These values should not be used for any
   functional decisions.
 
+Performance Feedback:
 * feedback_ctrs : Includes both Reference and delivered performance counter.
   Reference counter ticks up proportional to processor's reference performance.
   Delivered counter ticks up proportional to processor's delivered performance.
@@ -57,6 +69,22 @@ for each cpu X::
   (seconds).
 * reference_perf : Performance level at which reference performance counter
   accumulates (abstract scale).
+* perf_limited : Set when Delivered Performance has been constrained due to an
+  unpredictable event. It is not utilized when Autonomous Selection is enabled.
+
+Performance Controls:
+* max_perf : Maximum performance level at which the platform may run in the
+  range [Lowest Performance, Highest Performance], inclusive.
+* min_perf : Minimum performance level at which the platform may run in the
+  range [Lowest Performance, Highest Performance], inclusive but must be set
+  to a value that is less than or equal to that specified by the max_perf.
+* auto_sel : Enable Autonomous Performance Level Selection on this processor.
+* auto_activity_window : Indicates a moving utilization sensitivity window to
+  the platform’s autonomous selection policy.
+* energy_perf: Provides a value ranging from 0 (performance preference) to
+  0xFF (energy efficiency preference) that influences the rate of performance
+  increase /decrease and the result of the hardware's energy efficiency and
+  performance optimization policies.
 
 
 Computing Average Delivered Performance
-- 
2.25.1