[coreboot-gerrit] [XS] Change in coreboot[main]: mb/google/nissa/var/riven: Configure Acoustic noise mitigation

[David Wu (Code Review)]

Attention is currently required from: Dinesh Gehlot, Eric Lai, Jayvik Desai, Kapil Porwal, Nick Vaccaro, Paul Menzel, Subrata Banik.

David Wu has posted comments on this change by David Wu. ( https://review.coreboot.org/c/coreboot/+/84908?usp=email )

Change subject: mb/google/nissa/var/riven: Configure Acoustic noise mitigation
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Patch Set 3:

(2 comments)

Commit Message:

https://review.coreboot.org/c/coreboot/+/84908/comment/6818a84b_af987029?usp... :
PS2, Line 9: - Enable Acoustic noise mitigation
           : - Set slow slew rate VCCIA and VCCGT to SLEW_FAST_4
           : - Set FastPkgCRampDisable VCCIA and VCCGT to 1
> How did you determine these values?

From power team suggested in b/376165743#comment2
> We had tried the following solutions to reduce the EE acoustic noise.
> Change the CPU slew rate form 1/2 to 1/4.
> Stuff POSCAPs 150uF on VCCCORE(C620) and VCCGT(C621) power rail.
>
> According to the attachment, the acoustic noise can be improved a lot.

https://review.coreboot.org/c/coreboot/+/84908/comment/d4bd4996_62026436?usp... :
PS2, Line 14: TEST=build FW and check fsp log.
> Shouldn’t the “noise” also be measured somehow?

Done.