[S] Change in coreboot[master]: soc/amd/mendocino: Force resets to be cold

[Martin L Roth (Code Review)]

Attention is currently required from: Jason Glenesk, Raul Rangel, Matt DeVillier, Tim Van Patten, Fred Reitberger.

Martin L Roth has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/72486 )

Change subject: soc/amd/mendocino: Force resets to be cold
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Patch Set 3:

(1 comment)

File src/soc/amd/mendocino/fch.c:

https://review.coreboot.org/c/coreboot/+/72486/comment/88e11c9c_ce02f3e6 
PS3, Line 131: 	pm_write16(PWR_RESET_CFG, pm_read16(PWR_RESET_CFG) | TOGGLE_ALL_PWR_GOOD);
> no, fch_init_resets is essential to make sure that that bit to change the reset behavior is still se […]

fch_init_resets() is there so that when Linux does a reset, it's a cold reset.  This is identical to the situation on Cezanne.  If it's not there, the system will hang on reboot after S0i3.  That's the specific fix that this patch is intended to fix.  The warm resets in coreboot haven't been an issue, and we could probably leave that part of this change out, but it definitely doesn't hurt to have it in there as well.

This patch is correct to fix the bug it's addressing.