[XS] Change in coreboot[main]: mb/google/{rex,ovis}: Decrease EPP to 45% for MTL performance expecta...

[Sukumar Ghorai (Code Review)]

Attention is currently required from: Dinesh Gehlot, Eran Mitrani, Kapil Porwal, Paul Menzel, Sukumar Ghorai, Tarun.

Hello Dinesh Gehlot, Eran Mitrani, Kapil Porwal, Subrata Banik, Tarun, build bot (Jenkins),

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

https://review.coreboot.org/c/coreboot/+/79386?usp=email

to look at the new patch set (#5).

Change subject: mb/google/{rex,ovis}: Decrease EPP to 45% for MTL performance expectation
......................................................................

mb/google/{rex,ovis}: Decrease EPP to 45% for MTL performance expectation

The default EPP is set at 50%, which is deemed insufficiently
aggressive for meeting the MTL performance expectations in
balance_performance mode.

# cat /sys/devices/system/cpu/cpu0/cpufreq/energy_performance_preference
    balance_performance
    # iotools rdmsr 0 0x774
    0x0000000080003f06

EPP=45% is giving the required performance in MTL.
    # iotools rdmsr 0 0x774
    0x0000000073003d06

NOTE: Kernel changes are necessary to ensure that the EPP (Energy Performance Preference) configured in the BIOS is not overwritten: https://patchwork.kernel.org/patch/13461932

BUG=b:314275133
TEST=Build and boot.

Change-Id: I1953994cdb4e9363fdd4b4728e3e5236276c06c8
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
2 files changed, 8 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/86/79386/5