[coreboot-gerrit] [M] Change in coreboot[main]: soc/intel/alderlake: Add function to force disable memory channels

[Jamie Chen (Code Review)]

Attention is currently required from: Christian Walter, Dinesh Gehlot, Jayvik Desai, Jeremy Soller, Kapil Porwal, Lean Sheng Tan, Michał Kopeć, Michał Żygowski, Nick Vaccaro, Paul Menzel, Piotr Król, Sean Rhodes, Tim Crawford.

Jamie Chen has posted comments on this change by Kapil Porwal. ( https://review.coreboot.org/c/coreboot/+/85529?usp=email )

Change subject: soc/intel/alderlake: Add function to force disable memory channels
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Patch Set 6:

(1 comment)

File src/soc/intel/alderlake/meminit.c:

https://review.coreboot.org/c/coreboot/+/85529/comment/8e7f6dbe_37893d57?usp... :
PS1, Line 252: 	if (ch_disable_mask == 0) {
> I would think of switch case with fall through. Good pairing and Bad pairing with Bit indicator.

I think this CL is to provide an additional option to disable memory channels. Originally we could only use half_populated variable to turn off half of channels.
However, even with this CL to disable channels, users need still follow Intel PDG for proper usage.
We can skip checking these conditions because if config incorrect combinations, the FSP will return a "Memory initialization has failed" error. It's easy to identify.