Patchwork [4/6] intel_pstate: Use LFM bus ratio as min ratio/P state

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Submitter Colin King
Date March 4, 2014, 1:42 p.m.
Message ID <1393940533-29826-5-git-send-email-colin.king@canonical.com>
Download mbox | patch
Permalink /patch/326295/
State New
Headers show

Comments

Colin King - March 4, 2014, 1:42 p.m.
From: Dirk Brandewie <dirk.j.brandewie@intel.com>

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>
Cc: 3.13+ <stable@vger.kernel.org> # 3.13+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/cpufreq/intel_pstate.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Patch

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index e9de314f..1d1cafd 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -359,7 +359,7 @@  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)