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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2020-08-27 14:32:12 +0200
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2020-09-01 21:14:06 +0200
commitb388eb58ce47484a330681f09d1d058fe122c744 (patch)
tree148f489a6fc50b4292df4ae9a0f0d926d4646e37 /Documentation
parentc27a0ccc3c715c55fea6709eab2f9c6f551fcfaa (diff)
cpufreq: intel_pstate: Tweak the EPP sysfs interface
Modify the EPP sysfs interface to reject attempts to change the EPP to values different from 0 ("performance") in the active mode with the "performance" policy (ie. scaling_governor set to "performance"), to avoid situations in which the kernel appears to discard data passed to it via the EPP sysfs attribute. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Reviewed-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/admin-guide/pm/intel_pstate.rst4
1 files changed, 3 insertions, 1 deletions
diff --git a/Documentation/admin-guide/pm/intel_pstate.rst b/Documentation/admin-guide/pm/intel_pstate.rst
index cdd1a9a7f9a2..5072e7064d13 100644
--- a/Documentation/admin-guide/pm/intel_pstate.rst
+++ b/Documentation/admin-guide/pm/intel_pstate.rst
@@ -123,7 +123,9 @@ Energy-Performance Bias (EPB) knob (otherwise), which means that the processor's
internal P-state selection logic is expected to focus entirely on performance.
This will override the EPP/EPB setting coming from the ``sysfs`` interface
-(see `Energy vs Performance Hints`_ below).
+(see `Energy vs Performance Hints`_ below). Moreover, any attempts to change
+the EPP/EPB to a value different from 0 ("performance") via ``sysfs`` in this
+configuration will be rejected.
Also, in this configuration the range of P-states available to the processor's
internal P-state selection logic is always restricted to the upper boundary