[XS] Change in coreboot[main]: mb/google/{rex,ovis}: Disable package C-state auto demotion

[Sukumar Ghorai (Code Review)]

Attention is currently required from: Eran Mitrani, Eric Lai, Kapil Porwal, Subrata Banik, Tarun.

Hello Eran Mitrani, Eric Lai, Kapil Porwal, Subrata Banik, Tarun, build bot (Jenkins),

I'd like you to reexamine a change. Please visit

https://review.coreboot.org/c/coreboot/+/78250?usp=email

to look at the new patch set (#4).

The following approvals got outdated and were removed:
Code-Review+1 by Eric Lai, Code-Review+1 by Subrata Banik, Verified+1 by build bot (Jenkins)

Change subject: mb/google/{rex,ovis}: Disable package C-state auto demotion
......................................................................

mb/google/{rex,ovis}: Disable package C-state auto demotion

Package C-state auto demotion feature allows hardware to determine lower
C-state as per platform policy. Since platform sets performance policy
to balanced from hardware, auto demotion can be disabled without
performance impact.

Also, disabling this feature results soc to enter below PC8 state and
additional power savings ~30mW in Local-Video-Playback scenario.

BUG=b:303546334
TEST=Local build successfully & Boot to OS successfully
 - Also check platform enter PC8 state in local video playback
 - before this change: # iotools rdmsr 0 0xE2 -> 0x0000000060008008
 - After # iotools rdmsr 0 0xE2 -> 0x0000000000008008

Change-Id: Ia4cf4a7cb6bd5eaae26197b55f9385c078960d7b
Signed-off-by: Sukumar Ghorai 
---
M src/mainboard/google/rex/variants/baseboard/ovis/devicetree.cb
M src/mainboard/google/rex/variants/baseboard/rex/devicetree.cb
M src/soc/intel/meteorlake/chip.h
M src/soc/intel/meteorlake/fsp_params.c
4 files changed, 9 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/50/78250/4