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intel_idle: Disable Baytrail Core and Module C6 auto-demotion 

Power efficiency improves on Baytrail (Intel Atom Processor E3000)
when Linux disables C6 auto-demotion.

Based on work by Srinidhi Kasagar <srinidhi.kasagar@intel.com>.

Signed-off-by: Len Brown <len.brown@intel.com>
Cc: x86@kernel.org
This commit is contained in:
Len Brown 2014-07-31 15:21:24 -04:00
parent 19583ca584
commit 8c058d53f6
2 changed files with 10 additions and 0 deletions
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3
arch/x86/include/uapi/asm/msr-index.h
View File

@ -149,6 +149,9 @@
#define MSR_CORE_C1_RES 0x00000660
#define MSR_CC6_DEMOTION_POLICY_CONFIG 0x00000668
#define MSR_MC6_DEMOTION_POLICY_CONFIG 0x00000669
#define MSR_AMD64_MC0_MASK 0xc0010044
#define MSR_IA32_MCx_CTL(x) (MSR_IA32_MC0_CTL + 4*(x))

7
drivers/idle/intel_idle.c
View File

@ -89,6 +89,7 @@ struct idle_cpu {
* Indicate which enable bits to clear here.
*/
unsigned long auto_demotion_disable_flags;
bool byt_auto_demotion_disable_flag;
bool disable_promotion_to_c1e;
};
@ -613,6 +614,7 @@ static const struct idle_cpu idle_cpu_snb = {
static const struct idle_cpu idle_cpu_byt = {
.state_table = byt_cstates,
.disable_promotion_to_c1e = true,
.byt_auto_demotion_disable_flag = true,
};
static const struct idle_cpu idle_cpu_ivb = {
@ -814,6 +816,11 @@ static int __init intel_idle_cpuidle_driver_init(void)
if (icpu->auto_demotion_disable_flags)
on_each_cpu(auto_demotion_disable, NULL, 1);
if (icpu->byt_auto_demotion_disable_flag) {
wrmsrl(MSR_CC6_DEMOTION_POLICY_CONFIG, 0);
wrmsrl(MSR_MC6_DEMOTION_POLICY_CONFIG, 0);
}
if (icpu->disable_promotion_to_c1e) /* each-cpu is redundant */
on_each_cpu(c1e_promotion_disable, NULL, 1);