[Intel-gfx] [PATCH 1/3] drm/i915: Fix MI_DISPLAY_FLIP plane select offset on Ivybridge.

[Kenneth Graunke]

On 06/08/2011 02:36 AM, Chris Wilson wrote:
> On Tue, 07 Jun 2011 17:55:05 -0700, Kenneth Graunke<kenneth at whitecape.org>  wrote:
>> On 06/07/2011 04:14 PM, Keith Packard wrote:
>>> What's this last DWORD supposed to be for? The IVB spec says length
>>> should be '1' and there should be only 3 DWORDS in this command.
>>
>> Good question.  My reading of the docs say that it should be 3 DWORDs on
>> SNB as well; this code was directly lifted from "case 6" above (save the
>> first line).
>
> In my ancient copy of the specs, MI_DISPLAY_FLIP is 4 dwords, with this
> last dword for programming the panel-fitter and pipesrc. And it also
> says that command is applicable to IVB, but as I said it is an ancient
> copy.
> -Chris

That's correct.  SNB /does/ include a 4th DWord as you describe---newer 
specs got mangled and lost that info, somehow.  Argh.

IVB does only use three DWords, so the last OUT_RING should be nixed. 
Removing that does change the behavior, but doesn't yet make it work.

Thanks!
--Kenneth