[Intel-gfx] [PATCH] drm/i915/bdw: Use timeout mode for RC6 on bdw

[Ben Widawsky]

On Fri, Apr 11, 2014 at 11:00:38AM +0200, Daniel Vetter wrote:
> On Thu, Apr 10, 2014 at 08:29:55PM +0000, O'Rourke, Tom wrote:
> > >> > Higher RC6 residency is observed using timeout mode instead of EI
> > >> > mode.  This applies to Broadwell only.
> > >> > The difference is particularly noticeable with video playback.
> > >> >
> > >> > Issue: VIZ-3778
> > >> > Change-Id: I62bb12e21caf19651034826b45cde7f73a80938d
> > >> > Signed-off-by: Tom O'Rourke <Tom.O'Rourke at intel.com>
> > >>
> > >> How recent a nightly branch have you used to obtain these results?
> > >> Chris just fixed some serious bugs in the gpu booster logic which
> > >> would have affected all intermediate workloads.
> > >> -Daniel
> > >
> > >He must not be using nightly if he has any BDW RC6 residency at all.
> > >
> > [TOR:] Ben is correct.  I was testing mostly with a kernel for Android.
> > I also tested with Ben's broadwell branch and saw similar improvement.
> 
> Ok I think it'd be good to have this when we actually merge/enable the
> final pieces of the bdw rc6 code. Can you please work together with Ben to
> make sure this patch isn't lost?
> 
> Or who is shepherding bdw rc6 nowadays?
> -Daniel

Locally, people are still using my RC6 "workaround." We're waiting on
Mika at the moment. I am going to merge this patch to my
bdw-rc6/broadwell branches.

I think it would be great to get a little more detail under what
circumstances this improves residency. We can discuss that internally.

-- 
Ben Widawsky, Intel Open Source Technology Center