Change in coreboot[master]: mb/google/zork: fine tune stamp_boost parameter for gumboz

[Patrick Georgi (Code Review)]

Patrick Georgi has submitted this change. ( https://review.coreboot.org/c/coreboot/+/52313 )

Change subject: mb/google/zork: fine tune stamp_boost parameter for gumboz
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mb/google/zork: fine tune stamp_boost parameter for gumboz

The new discovery from Google & AMD, the value currently used
STAPM Time Constant of 1640 is reducing real PPT TSP from the
target 4.8W to 4.68W.

Furthermore, when using the "default" STAPM Time Constant of 1400,
the actual real PPT TSP becomes 4.89W.

Operating at this default settings therefore uses a higher real PPT TSP,
which results in a significant performance improvement.

BUG=b:184902568
BRANCH=zork
TEST=1. emerge-zork coreboot
     2. run balance performance and skin temperature test => pass

Signed-off-by: Kevin Chiu 
Change-Id: I102c1c5f8215a6c5f7a4451f5731167c32e27c90
Reviewed-on: https://review.coreboot.org/c/coreboot/+/52313
Reviewed-by: Sam McNally 
Reviewed-by: Kangheui Won 
Tested-by: build bot (Jenkins) 
---
M src/mainboard/google/zork/variants/gumboz/overridetree.cb
1 file changed, 1 insertion(+), 1 deletion(-)

Approvals:
  build bot (Jenkins): Verified
  Kangheui Won: Looks good to me, approved
  Sam McNally: Looks good to me, approved

diff --git a/src/mainboard/google/zork/variants/gumboz/overridetree.cb b/src/mainboard/google/zork/variants/gumboz/overridetree.cb
index 7139ac8..5675487 100644
--- a/src/mainboard/google/zork/variants/gumboz/overridetree.cb
+++ b/src/mainboard/google/zork/variants/gumboz/overridetree.cb
@@ -12,7 +12,7 @@
    register "slow_ppt_limit_mW" = "6000"
    register "fast_ppt_limit_mW" = "9000"
    register "slow_ppt_time_constant_s" = "5"
-	register "stapm_time_constant_s" = "1640"
+	register "stapm_time_constant_s" = "1400"
    register "sustained_power_limit_mW" = "4800"

register "telemetry_vddcr_vdd_slope_mA" = "41322"