[Intel-gfx] [PATCH] drm/i915: Sanitize BIOS debugging bits from PIPECONF

Eugeni Dodonov eugeni at dodonov.net
Thu Mar 22 16:40:53 CET 2012

On Thu, Mar 22, 2012 at 12:00, Chris Wilson <chris at chris-wilson.co.uk>wrote:

> Quoting the BSpec from time immemorial:
>  PIPEACONF, bits 28:27: Frame Start Delay (Debug)
>  Used to delay the frame start signal that is sent to the display planes.
>  Care must be taken to insure that there are enough lines during VBLANK
>  to support this setting.
> An instance of the BIOS leaving these bits set was found in the wild,
> where it caused our modesetting to go all squiffy and skewiff.

Just complementing Chris patch and calling for some testing in the wild...

For the ones affected by the latest VBIOS update on Ivy Bridge which
resulted in somewhat strange display issues, could you please test this
patch and verify if it fixes the issue for you?

Eugeni Dodonov
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