Sumeet R Pawnikar has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/41425 )
Change subject: [TEST] Helios: Add fan speed control for TSR3 sensor with DPTF settings ......................................................................
Patch Set 4:
(1 comment)
https://review.coreboot.org/c/coreboot/+/41425/4/src/mainboard/google/hatch/... File src/mainboard/google/hatch/variants/helios/include/variant/acpi/dptf.asl:
https://review.coreboot.org/c/coreboot/+/41425/4/src/mainboard/google/hatch/... PS4, Line 93: 100
The 100 is weight. Since every thing is 100, there is no effect here. […]
Here these entreies are 90, 80, 60,...,10 are the mapped control points for DFPS. When TSR3 temp (temperature) is below 44C (as per last active threshold *_AC6) defined value above at line 37, fan will be off. => When TSR3 temp hits 44C (as per active threshold *_AC6 at line 37), fan will start rotating for mapped AC6 entry in this DART table which is 10 value here. Based on this 10 value, it maps to control point in DFPS table to 10 at line 65 and fan runs at 800 rpm. => Now if TSR3 temp still increases and reaches to 45C (as per next active threshold *_AC5 at line 36), fan speed will increase. Now, this *_AC5 temp entry mapped to 20 in this DART teble. And this maps to control point in DFPS table to 20 at line 64 and fun speed increases to 1608 rpm. => This way if temp keeps increasing to next *_ACx threshold, the fan speed will increases and runs at higher speed following this *ACx value in this DART table and maps to control value and speed rpm value. => Also, whenever temp goes below particular *_ACx threshold, it follows the similar mechanism and mapping and fan speed slows down to lower value. Hope, I am able to explain this flow in most simpler way.