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
diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index 4d140bb..2d23cf8 100644
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -89,6 +89,7 @@
* 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_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 @@
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);