Random freezes in Windows 11

[mkopec]

Device

NovaCustom *

Dasharo version

v1.5.1 TGL, v1,7,1 ADL

Affected component(s) or functionality

Stability, power delivery, sleep mode

Brief summary

Windows sometimes freezes in rendom moments, most often at the login screen or in sleep mode

How reproducible

~10%

How to reproduce

• Boot into Windows 11
• Wait in the login prompt
  or:
• Put laptop to sleep

Expected behavior

Windows completely freezes, if sleeping, the laptop won't wake up again. Need to reset by holding down the power button.

Actual behavior

No random freezes

Screenshots

No response

Additional context

No response

Solutions you've tried

No response

[mkopec]

This was a fun one:

When connected to an EC debugger, the issue would no longer be reproducible. But looking at the EC logs, I saw that when windows is idling or sleeping, it may very rapidly enter and exit C-state C10, causing very noticeable coil whine. When this is happening, the EC may report some signals randomly flipping up and down (!) like the ACIN# signal for power supply detection.

I guessed that the two are related and enabled Acoustic Noise Mitigation, disabled Fast Package C-state ramp, and filled in the missing voltage regulator params. This reduced coil whine a lot and seemingly fixed these random freezes. Should also improve efficiency a bit, while it might also hurt C-state residency a bit, but not noticeably enough in my testing.

Related commits:

• Dasharo/coreboot@66620e6
• Dasharo/coreboot@2e3d964
• Dasharo/coreboot@cad41c1
• Dasharo/coreboot@ca9a0b3

Note that the nv40mz service manual does not have ICCMax, loadline or OCP values listed anywhere, so I skipped the VR configs on that model.