[Intel-gfx] [PATCH 4/4] drm/i915: re-enable rc6 for ironlake

[Chris Wilson]

On Wed, 27 Apr 2011 14:20:09 -0700, Jesse Barnes <jbarnes at virtuousgeek.org> wrote:
> On Wed, 27 Apr 2011 08:49:28 +0100
> Chris Wilson <chris at chris-wilson.co.uk> wrote:
> 
> > On Fri, 18 Mar 2011 16:12:48 -0700, Ben Widawsky <ben at bwidawsk.net> wrote:
> > > The previous patches should fix enough of the known issues to try
> > > re-enabling rc6 for general consumption
> > 
> > Yay, and they bring back the old bugs! :)
> > 
> > So upon enabling fbc on a 2560x1440 external panel, it goes blank again.
> > The same symptoms as prompted disabling fbc last year.  Can anyone confirm
> > this bad behaviour?
> 
> Re-enabling rc6 causes problems when you enable fbc?

Yes, I'm pretty sure that's the causal link. Disabling the LVDS makes the
external DP go haywire, with fbc enabled for the external, but worked fine
until we tried to enable rc6 again. If I remember my bugs correctly, pure
fbc failures resulted in a stripy display, whereas this is a solid
corruption. And I'm pretty certain this is the same bug that convinced me
to disable rc6 the last time.
 
> We should probably just enable fbc on the pipe connected to the
> internal panel (if any) and keep it disabled otherwise.

On Arrandale, fbc is potentially a bigger win than rc6 - but is also a
potential loss - right?
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre