[PATCH v2] cpufreq-stats: document limitations on modern cpufreq drivers

[NicoErdmann <nicobsc4@yahoo.com>]

Add a note clarifying that cpufreq-stats may not be present or may not provide meaningful statistics depending
on the active CPU frequency scaling driver.

In particular, drivers such as intel_pstate and amd_pstate may use alternative mechanisms for frequency scaling
and accounting.

v2:
 - Add missing period at end of sentence (reported by Randy)

Signed-off-by: NicoErdmann <nicobsc4@yahoo.com>
---
 Documentation/cpu-freq/cpufreq-stats.rst | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Documentation/cpu-freq/cpufreq-stats.rst b/Documentation/cpu-freq/cpufreq-stats.rst
index 9ad695b1c7db..6ffa5a6a63c9 100644
--- a/Documentation/cpu-freq/cpufreq-stats.rst
+++ b/Documentation/cpu-freq/cpufreq-stats.rst
@@ -28,6 +28,13 @@ Various statistics will form read_only files under this directory.
 This driver is designed to be independent of any particular cpufreq_driver
 that may be running on your CPU. So, it will work with any cpufreq_driver.
 
+.. note::
+	
+   On some modern systems, this interface may not be available or may not
+   expose meaningful statistics depending on the active CPU frequency scaling driver.
+
+   In particular, drivers such as intel_pstate or amd_pstate may use alternative
+   mechanisms for frequency scaling and accounting.
 
 2. Statistics Provided (with example)
 =====================================
-- 
2.54.0