From: Dirk Brandewie <dirk.j.brandewie@intel.com>
Date: Wed, 12 Feb 2014 18:01:06 +0000 (-0800)
Subject: intel_pstate: Use LFM bus ratio as min ratio/P state
X-Git-Tag: v3.13.6~55
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=55e02d0a3383b15d1fcff130f83c0096e22a19b2;p=thirdparty%2Fkernel%2Fstable.git

intel_pstate: Use LFM bus ratio as min ratio/P state

commit 4042e7570cff740460b75c6fc604c629621d3dd2 upstream.

LFM (max efficiency ratio) is the max frequency at minimum voltage
supported by the processor.  Using LFM as the minimum P state
increases performmance without affecting power. By not using P states
below LFM we avoid using P states that are less power efficient.

Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index d51f17ed691e0..aa366ece2d4bd 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -348,7 +348,7 @@ static int byt_get_min_pstate(void)
 {
 	u64 value;
 	rdmsrl(BYT_RATIOS, value);
-	return value & 0xFF;
+	return (value >> 8) & 0xFF;
 }
 
 static int byt_get_max_pstate(void)