Bug #32

[Haswell/Broadwell] LPC power optimizer RCBA instructions break eDP display with Intel VBIOS

Added by CoolStar Organization over 3 years ago. Updated over 2 years ago.

Status:ClosedStart date:02/06/2016
Priority:NormalDue date:
Assignee:-% Done:


Target version:-


With the Intel VBIOS other than version 2070 run by SeaBIOS, or with Windows's Intel HD Graphics driver, an LPC power optimizer setting breaks eDP on Haswell/Broadwell.

Affected Haswell code: https://github.com/coreboot/coreboot/blob/master/src/southbridge/intel/lynxpoint/lpc.c#L349
Affected Broadwell code: https://github.com/coreboot/coreboot/blob/master/src/soc/intel/broadwell/lpc.c#L285

Removing the power optimizer lines fixes eDP display on Haswell/Broadwell.


#1 Updated by CoolStar Organization about 3 years ago

Also, with the Tianocore payload, the Intel GOP driver is affected by the same issue with eDP. The same patch also fixes the issue with the UEFI GOP driver.

#3 Updated by Martin Roth over 2 years ago

  • Status changed from New to Closed

Patch is merged. Closing the issue.

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