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

[Ben Widawsky]

On Wed, Apr 27, 2011 at 03:49:40PM -0700, Jesse Barnes wrote:
> On Wed, 27 Apr 2011 23:03:14 +0100
> Chris Wilson <chris at chris-wilson.co.uk> wrote:
> > > 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?
> 
> No, I think rc6 is still a much bigger win even on Arrandale (iirc >>1W
> for rc6, ~0.5W for fbc best case).  And yeah, there is the potential for
> increased power consumption when fbc is enabled if a framebuffer that
> doesn't compress very well continues to get re-compressed over a long
> period of time.
> 
> Jesse

The last tests that I ran it seemed we needed to be really careful about
when to turn on FBC on for Arrandale as noted in the bug that Chris
assigned to me below :). I did some rc6 tests prior to the FBC tests and
can't find my notes, but I actually recall it being closer to 2W.

https://bugs.freedesktop.org/show_bug.cgi?id=31742

Ben