[Intel-gfx] [PATCH] drm/i915: always set FDI composite sync bit

[Adam Jackson]

On 10/10/11 7:22 PM, Keith Packard wrote:
> On Mon, 10 Oct 2011 14:28:52 -0700, Jesse Barnes<jbarnes at virtuousgeek.org>  wrote:
>
>> It's needed for 3 pipe support as well as just regular functionality
>> (e.g. DisplayPort).
>
> Any explanation on how you get sync without this? As in, why did this
> ever work?

To a first approximation, it didn't.  I was never able to get anything 
reliably lit up besides the boot output (and only that one; hotplug 
after was a disaster).

I don't have register dumps handy to compare BIOS setup with this 
change, but I could if needed.

It still seems entirely magical and probably wrong in some situations. 
And I'm thrilled to see that PPT is functionally different from CPT 
(seriously, stop doing that) instead of just moving bit definitions 
around (seriously, stop doing that).  But this change is massively 
better than before.

- ajax