Julius Werner has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/32397 )
Change subject: mediatek/mt8183: Set CPU frequency to 1989MHz ......................................................................
Patch Set 3:
Be careful that you maintain causality here! You have to *first* increase the CPU voltage, make sure there's enough time for it to stabilize, and *then* increase the CPU frequency. As far as I can tell your mt6358_init() runs in romstage but your mt_pll_init() already runs in the bootblock, so you'll run half of your firmware with an undervolted CPU!
You'll want to either pull (at least some of) the PMIC init into the bootblock, or create an extra function to increase the CPU frequency later in romstage. The latter is what we did on MT8173 (see mt_pll_raise_ca53_freq()) and is generally much safer (because then you can RW update it if necessary), so I'd recommend to do that unless you determine that the extra CPU speed in verstage really makes a significant speed impact.
(Also, we've had some regulator overshoot problems on other boards in the past when we increased the CPU voltage too quickly... you may want to scope the voltage when running this code to confirm it doesn't overshoot.)