[Intel-gfx] [PATCH] drm/i915: [GEN7] Use HW scheduler for fixed function shaders

[Daniel Vetter]

Jesse, can you also please check whether we need the same thing on vlv?
atm the the clock gating functions are almost identical safe for this wrt
touching registers in the gt core.
-Daniel

On Sun, Apr 15, 2012 at 10:14:24AM -0700, Ben Widawsky wrote:
> On Sun, 15 Apr 2012 11:55:36 -0300
> Eugeni Dodonov <eugeni at dodonov.net> wrote:
> 
> > On Sat, Apr 14, 2012 at 22:41, Ben Widawsky <ben at bwidawsk.net> wrote:
> > 
> > > This originally started as a patch from Bernard as a way of simply
> > > setting the VS scheduler. After submitting the RFC patch, we
> > > decided to also modify the DS scheduler. To be most explicit, I've
> > > made the patch explicitly set all scheduler modes, and included the
> > > defines for other modes (in case someone feels frisky later).
> > >
> > > The rest of the story gets a bit weird. The first version of the
> > > patch showed an almost unbelievable performance improvement. Since
> > > rebasing my branch it appears the performance improvement has gone,
> > > unfortunately. But setting these bits seem to be the right thing to
> > > do given that the docs describe corruption that can occur with the
> > > default settings.
> > >
> > > In summary, I am seeing no more perf improvements (or regressions)
> > > in my limited testing, but we believe this should be set to prevent
> > > rendering corruption, therefore cc stable.
> > >
> > > v1: Clear bit 4 also (Ken + Eugeni)
> > > Do a full clear + set of the bits we want (Me).
> > >
> > > Cc: Bernard Kilarski <bernard.r.kilarski at intel.com>
> > > Cc: stable <stable at vger.kernel.org>
> > > Reviewed-by (RFC): Kenneth Graunke <kenneth at whitecape.org>
> > > Signed-off-by: Ben Widawsky <benjamin.widawsky at intel.com>
> > >
> > 
> > Very nice!
> > 
> > I also suspect that maybe the initial performance improvement you've
> > seen with previous testing could be related to the occasional turbo
> > disabling we've been seeing in other cases as well (e.g.,
> > https://bugs.freedesktop.org/show_bug.cgi?id=44006).
> > 
> > But as for this patch, I have just one comment/suggestion below, but
> > other than that:
> > 
> > Reviewed-by: Eugeni Dodonov <eugeni.dodonov at intel.com>
> > 
> > +static void gen7_setup_fixed_func_scheduler(struct drm_i915_private
> > > *dev_priv)
> > >
> > 
> > Perhaps this functions should be named
> > ivybridge_setup_fixed_func_scheduler instead?
> > 
> > Even if those bits are not ivy bridge-exclusive, this specific
> > explicit setup applies to ivb only..
> > 
> 
> I wasn't sure if we wanted this for VLV or not. In fact, originally the
> patch did call this in the VLV setup, but since I decided to CC stable
> (per Ken's idea) I removed the VLV part.
> 
> If Jesse, or someone could confirm we don't want this for VLV, I agree
> with your commen, and I'd probably just go back and inline the register
> write. FWIW, it does *seem* like we don't want to set this on HSW.
> 
> Anyway, thanks for your review.
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-- 
Daniel Vetter
Mail: daniel at ffwll.ch
Mobile: +41 (0)79 365 57 48