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[v2] intel_pstate: Use LFM bus ratio as min ratio/P state

Message ID 1392834925-21648-1-git-send-email-dirk.j.brandewie@intel.com (mailing list archive)
State Accepted, archived
Headers show

Commit Message

dirk.brandewie@gmail.com Feb. 19, 2014, 6:35 p.m. UTC 
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>
---
 drivers/cpufreq/intel_pstate.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Rafael J. Wysocki Feb. 20, 2014, 12:44 a.m. UTC | #1 
On Wednesday, February 19, 2014 10:35:25 AM dirk.brandewie@gmail.com wrote:
> 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>

Thanks!  I've replaced the original changelog with the one above.

> ---
>  drivers/cpufreq/intel_pstate.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
> index b80c03d..ff45ce1 100644
> --- a/drivers/cpufreq/intel_pstate.c
> +++ b/drivers/cpufreq/intel_pstate.c
> @@ -356,7 +356,7 @@ 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)
>
diff mbox

Patch

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index b80c03d..ff45ce1 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -356,7 +356,7 @@  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)