[coreboot] T530: Cleaning Intel ME currently does not work <--> CPU fan won't start

[Nico Huber]

On 24.07.2017 22:33, David Hobach wrote:
>> P.S.: Just tested the current ME-cleaner version with the OEM BIOS
>> version: The CPU fan did spin - even after hard resets.
>>
>> So
>> a) The issue is only related to coreboot.
>> b) It is possible to do better here.
> 
> I gave it one last shot and externally re-flashed the coreboot image
> with cleaned ME and... well the CPU fan worked even after several hard
> resets.
> 
> At first I thought I'm stupid and then I tried the following:
> 
> Internally re-flash with the coreboot version with ME --> CPU fan worked
> as expected (I had ME after all).
> 
> Internally re-flash with the coreboot image with cleaned ME from above.
> --> After some hard resets the CPU fan stopped working as I had
> experienced it before.
> 
> Internally re-flash with the OEM BIOS version with cleaned ME. --> CPU
> fan worked again after some hard resets.
> 
> Externally re-flash with the coreboot version with cleaned ME without
> CMOs battery. --> CPU fan still worked after 3-4 hard resets. --> SUCCESS!
> 
> In short: Flashing the OEM version with cleaned ME *before* flashing
> coreboot seems to fix the issue.
> If you flash from the OEM version with ME, you'll run into the issue
> after some hard resets...
> 
> I don't really understand why, but I'll certainly enjoy the results!
> ... and a beer now. 
This is somehow what I already expected after your last mail. Flashing
the cleaned ME firmware alone leaves the ME in a bad state. The vendor
BIOS seems to know a way to fix that. coreboot doesn't? I've never
looked close at the code, maybe we just miss a global reset at some
point.

If you want to go on, you can compare the output of `intelmetool` for
the good and bad states with cleaned ME. I'm not sure if it will show
a difference, but if we're lucky, it might give us a hint how to fix
it.

Nico