linux-kernel - Re: [PATCH] drm/i915: By default, enable RC6 on IVB and SNB when reasonable

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Date:	Tue, 22 Nov 2011 20:51:45 +0000
From:	Matthew Garrett <mjg59@...f.ucam.org>
To:	Eugeni Dodonov <eugeni@...onov.net>
Cc:	Keith Packard <keithp@...thp.com>, intel-gfx@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH] drm/i915: By default, enable RC6 on IVB and SNB when
 reasonable

On Tue, Nov 22, 2011 at 06:46:21PM -0200, Eugeni Dodonov wrote:
> On Tue, Nov 22, 2011 at 18:15, Matthew Garrett <mjg@...hat.com> wrote:
> 
> > On Fri, Nov 18, 2011 at 10:41:29PM -0800, Keith Packard wrote:
> >
> > > +     /*
> > > +      * Only enable RC6 if all dma remapping is disabled, or if
> > > +      * there's no iommu present in the machine.
> > > +      */
> > > +     if (INTEL_INFO(dev)->gen == 6)
> > > +             return no_iommu || dmar_disabled;
> >
> > So the user has to choose between 5W of power saving or having dmar? And
> > we default to giving them dmar?
> 
> 
> From the latest investigations, it is either this, or random gpu hangs and
> crashes when both are enabled :(.

So blacklist dmar on sandybridge. The power saving is going to be more 
important for most users.

-- 
Matthew Garrett | mjg59@...f.ucam.org
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