[coreboot] Wired problems with Intel skylake based board

[Nico Huber]

On 10/16/18 9:46 AM, Christian Gmeiner wrote:
> Am Mo., 15. Okt. 2018 um 15:26 Uhr schrieb Naresh G. Solanki
> <naresh.solanki.2011 at gmail.com>:
>> For problem 1, can you give data on where exactly it hangs?, Is it in
>> OS or FW ?, Can you provide kernel/coreboot log, port 80 dump when it
>> hangs.
> 
> It only hangs If I change the following values:
> 
>     mem_cfg->PegDisableSpreadSpectrumClocking = 1;
>     mem_cfg->PchPmPciePllSsc = 0;
> 
> The 'physical' cause for the hang is also known: PLT_RST# never gets
> high again. There are chances
> that it does not hang but PCI devices (sata, usb hc, ...) are not
> working as expected as the PCe reference clock
> is in such a case at around 92 Mhz.

You said earlier that you can dump (but not change) the ICC settings,
right? Did you check what settings are made with PchPmPciePllSsc == 0?

If FSP ends up enabling it with a value of 0, I could imagine that this
is just unexpected / the result undefined. Did you try other values than
0? 1? I guess the value gives a percentage of a percentage; 0.01% down-
spread is probably not too bad.

And maybe somebody with access to the FSP source can document what it
does and if there is a switch (missing) to disabled it ;)

Nico