[S] Change in coreboot[main]: Documentation/mb/asus/p8z77-m: Document latest test results

[Keith Hui (Code Review)]

Attention is currently required from: Angel Pons, Kevin Keijzer, Paul Menzel.

Keith Hui has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/78204?usp=email )

Change subject: Documentation/mb/asus/p8z77-m: Document latest test results
......................................................................

Patch Set 2:

(1 comment)

File Documentation/mainboard/asus/p8z77-m.md:

https://review.coreboot.org/c/coreboot/+/78204/comment/491d1f07_ed7c19d1 :
PS2, Line 106: It appears all memory modules rated for DDR3-1600 will fail to boot if
             :   max_mem_clock_mhz is set to 800 in devicetree.
> @Angel I only have Ivy Bridge cpu's, so that's all I've tested.

We need auto downclocking.

How about using nvram? If we need to reset the ivy bridge to set a new memory frequency, it is not surprising its scratchpads would get wiped too.

I am about to make more updates to this doc - yesterday I was able to boot one stick of DDR3-1600 laptop ram at 800mhz after changing frequency back to 800 in devicetree, but the 2nd stick of 4GB+ memory would fail training and be disabled. If it's on the same channel as the first stick, the whole machine dies.