[coreboot-gerrit] Change in coreboot[master]: soc/intel/cannonlake: Add chip config to override CPU flex ratio

[Subrata Banik (Code Review)]

Subrata Banik has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/36864 )

Change subject: soc/intel/cannonlake: Add chip config to override CPU flex ratio
......................................................................

Patch Set 6:

(1 comment)

https://review.coreboot.org/c/coreboot/+/36864/2/src/soc/intel/cannonlake/ro... 
File src/soc/intel/cannonlake/romstage/fsp_params.c:

https://review.coreboot.org/c/coreboot/+/36864/2/src/soc/intel/cannonlake/ro... 
PS2, Line 79: 	flex_ratio = rdmsr(MSR_FLEX_RATIO);
> If I understand the EDS correctly, this register's contents survive a reset. […]

no, not like that, this register always hold the snap shot of what cpu softstap has set. By passing CpuRatio UPD we are actually overriding that cpu softstrap which also could have programmed using FIT. But its good practice to avoid FIT and use more code to set this. Condition that it will hit a reset if FIT cpu softstrap and given overriden values are not same, So it will override new value and hit a soft reset to apply the same freq for cpu. Thats the reason its written sticky in BWG/SDM