[S] Change in coreboot[main]: cpu/intel/model_206ax: Allow package power limit clamping

[Anastasios Koutian (Code Review)]

Anastasios Koutian has posted comments on this change by Anastasios Koutian. ( https://review.coreboot.org/c/coreboot/+/83270?usp=email )

Change subject: cpu/intel/model_206ax: Allow package power limit clamping
......................................................................

Patch Set 8:

(1 comment)

Commit Message:

https://review.coreboot.org/c/coreboot/+/83270/comment/4669022e_02a607d6?usp... :
PS8, Line 12: Tested on ThinkPad T420 with the i7-3940XM.
> How can this be tested?

Please refer to this comment: https://review.coreboot.org/c/coreboot/+/83270/comment/c41532aa_f71a7182/

I tested this with the i7-3940XM, by running a combined stress test for CPU cores and integrated graphics:

`$ stress-ng -c 8 --cpu-method matrixprod`
`$ furmark --fullscreen --p1080 --demo furmark-gl`

With the PL1 clamp disabled, after several minutes of running the two commands simultaneously, the core frequency is 3.0 GHz, graphics frequency is 650 MHz, and package power consumption levels out at ~42 W.

When the PL1 clamp is enabled, for the same stress test, core frequency is 2.7 GHz, graphics are at 540 MHz, and package power stabilises at 35 W.