[coreboot-gerrit] Change in coreboot[master]: nb/amd/agesa/family14: Improve HTC threshold handling

[Michał Żygowski (Code Review)]

Michał Żygowski has submitted this change. ( https://review.coreboot.org/c/coreboot/+/39697 )

Change subject: nb/amd/agesa/family14: Improve HTC threshold handling
......................................................................

nb/amd/agesa/family14: Improve HTC threshold handling

According to BKDGs HTC temperature limit field indicates the threshold
where HTC becomes active. HTC active state means that processor is
limiting its power consumption and maximum P-State. Using this threshold
as _CRT is incorrect, since HTC active is designed to prevent
overheating, not causing immediate shutdown.

Change the behavior of temperature limit to act as a passive cooling
threshold. Make the passive cooling threshold a reference value for
critical and hot temperature with 5 degrees step.

TEST=boot FreeBSD on PC Engines apu2 and check the thermal zone
temperature using sysctl

Signed-off-by: Michał Żygowski 
Change-Id: Ife64c3aab76f8e125493ecc8183a6e87fb012e3b
Reviewed-on: https://review.coreboot.org/c/coreboot/+/39697
Tested-by: build bot (Jenkins) 
Reviewed-by: Nico Huber 
Reviewed-by: Angel Pons 
---
M src/northbridge/amd/agesa/family14/acpi/thermal_mixin.asl
1 file changed, 11 insertions(+), 3 deletions(-)

Approvals:
  build bot (Jenkins): Verified
  Nico Huber: Looks good to me, approved
  Angel Pons: Looks good to me, approved

diff --git a/src/northbridge/amd/agesa/family14/acpi/thermal_mixin.asl b/src/northbridge/amd/agesa/family14/acpi/thermal_mixin.asl
index 1f877cc..3c692ce 100644
--- a/src/northbridge/amd/agesa/family14/acpi/thermal_mixin.asl
+++ b/src/northbridge/amd/agesa/family14/acpi/thermal_mixin.asl
@@ -35,7 +35,7 @@
  */

#ifndef K10TEMP_HOT_OFFSET
-# define K10TEMP_HOT_OFFSET	100
+# define K10TEMP_HOT_OFFSET	50
 #endif

#define K10TEMP_KELVIN_OFFSET	2732
@@ -71,7 +71,11 @@
    	Return (Add (Local0, K10TEMP_KELVIN_OFFSET))
    }

-	Method (_CRT) {	/* Critical temp in tenths degree Kelvin. */
+	/*
+	 * TLMT indicates threshold where HTC become active. That is the processor will limit
+	 * P-State and power consumption in order to cool down.
+	 */
+	Method (_PSV) {	/* Passive temp in tenths degree Kelvin. */
    	Multiply (TLMT, 10, Local0)
    	ShiftRight (Local0, 1, Local0)
    	Add (Local0, K10TEMP_TLIMIT_OFFSET, Local0)
@@ -79,6 +83,10 @@
    }

Method (_HOT) {	/* Hot temp in tenths degree Kelvin. */
-		Return (Subtract (_CRT, K10TEMP_HOT_OFFSET))
+		Return (Add (_PSV, K10TEMP_HOT_OFFSET))
+	}
+
+	Method (_CRT) {	/* Critical temp in tenths degree Kelvin. */
+		Return (Add (_HOT, K10TEMP_HOT_OFFSET))
    }
 }