Change in coreboot[master]: mb/google/brya: Disable C state auto demotion for Brya & Brask

[Subrata Banik (Code Review)]

Attention is currently required from: Maulik V Vaghela, Tim Wawrzynczak.
Subrata Banik has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/62630 )

Change subject: mb/google/brya: Disable C state auto demotion for Brya & Brask
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Patch Set 5:

(2 comments)

Commit Message:

https://review.coreboot.org/c/coreboot/+/62630/comment/ef39b57c_b4588135 
PS5, Line 9: C state
C-state

https://review.coreboot.org/c/coreboot/+/62630/comment/cf62484b_58a5768d 
PS5, Line 13: disabling this feature results in 110 mW power savings
In general, deeper C-states such as C6 have long latencies and have higher energy entry/exit costs. The resulting performance and energy penalties become significant  when the entry/exit frequency of a deeper C-state is high. Therefore, incorrect or 
inefficient usage of deeper C-states have a negative impact on power. To increase residency and improve power in deeper C-states, the processor supports C-state auto-demotion since Sandy bridge.

This is what I read in ADL Processor EDS as well "The Processor may demote the Package C state to a shallower C state, for example instead of going into package C10, it will demote to package C8 (and so on as required). The processor decision to demote the package C state is based on the required C states latencies, entry/exit energy/power and devices LTR."

Have you measured the performance impact with this change ?