soc/intel/apollolake: enable MONITOR/MWAIT for GLK
MONITOR/MWAIT had an irremediable hardware bug for Apollolake.
This has been fixed for GLK. Therefore, make MONITOR/MWAIT based
C-states the default for GLK and disable IO-Redirection based
C-states used for Apollolake.
Tested on GLK w/kernel 4.14.27 using turbostat to observe C-state
residencies with and without load.
Tested for S0ix entry and exit using:
"echo freeze > /sys/power/state" and "suspend_stress_test -c 500".
BUG=b:77639897
Change-Id: If648c25a9b26c04b278dce4af241d439790288ca
Signed-off-by: Cole Nelson <colex.nelson@intel.com>
Signed-off-by: Venkateswarlu Vinjamuri <venkateswarlu.v.vinjamuri@intel.com>
Reviewed-on: https://review.coreboot.org/19718
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/soc/intel/apollolake/chip.c b/src/soc/intel/apollolake/chip.c
index 1dd6daf..cac2c00 100644
--- a/src/soc/intel/apollolake/chip.c
+++ b/src/soc/intel/apollolake/chip.c
@@ -565,9 +565,10 @@
silconfig->LPSS_S0ixEnable = cfg->lpss_s0ix_enable;
/* Disable monitor mwait since it is broken due to a hardware bug
- * without a fix
+ * without a fix. Specific to Apollolake.
*/
- silconfig->MonitorMwaitEnable = 0;
+ if (!IS_ENABLED(CONFIG_SOC_INTEL_GLK))
+ silconfig->MonitorMwaitEnable = 0;
silconfig->SkipMpInit = 1;