[coreboot] x86: best approach to debug consumer hardware?

[Andrey Korolyov]

>
> I'd expect the clockgen to be the culprit too. But this C-state number
> could be a typo and also be the reason for your trouble (though, I'd
> wonder why it works on the T60). This number is used to map ACPI C-state
> semantics to the states presented in _CST. ACPI knows three C states and
> those rarely match the actual C states of the hardware. Basically, a 3
> instead of a 2 tells ACPI to flush caches before entering this state.
> Also, ACPI C3 is to be avoided if bus-master activity is expected.
>

It turned out to be again very simple thing: by some reason yet to be
found, write within ics954309_init could succeed only for first eight
data addresses on this board, it would ultimately return nothing for
higher data addresses within 0x69 so boot which is trying to write
smbus-type-width block will hang as it has been reported earlier.
Magically, cutting chip initialization in this crude way appears to
work against C3 behavour. I would take a look on the exact PLL chip
model upon next disassembly and also would dump i2c data with vendor
BIOS to get this properly (vendor BIOS does prevent access to clock
generator bits, as well to SPD data, just to mention).

Forgot to mention that I`ve of course tried straightforward _CST fix
before, with no success at all. Someone with working T60/X60 could try
to check 'fixed' cst_entries ordering in mainboard.c and post the
results, right now all mine X60s are far away from the working state.