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authorLen Brown <len.brown@intel.com>2014-07-31 15:21:24 -0400
committerLen Brown <len.brown@intel.com>2014-08-15 17:06:14 -0400
commit8c058d53f6f2eb0b9cd3bc4ce5c053a64dded671 (patch)
treefb657c7092c97ce7452746008c2894ec17e481ae
parent19583ca584d6f574384e17fe7613dfaeadcdc4a6 (diff)
downloadlinux-8c058d53f6f2eb0b9cd3bc4ce5c053a64dded671.tar.gz
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
-rw-r--r--arch/x86/include/uapi/asm/msr-index.h3
-rw-r--r--drivers/idle/intel_idle.c7
2 files changed, 10 insertions, 0 deletions
diff --git a/arch/x86/include/uapi/asm/msr-index.h b/arch/x86/include/uapi/asm/msr-index.h
index fcf2b3ae1bf..4a7aecd2ea1 100644
--- a/arch/x86/include/uapi/asm/msr-index.h
+++ b/arch/x86/include/uapi/asm/msr-index.h
@@ -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))
diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index 4d140bbbe10..2d23cf8279f 100644
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -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);