Re: [PATCH] drm/i915: By default, enable RC6 on IVB and SNB whenreasonable

From: Matthew Garrett
Date: Tue Nov 22 2011 - 15:51:50 EST


On Tue, Nov 22, 2011 at 06:46:21PM -0200, Eugeni Dodonov wrote:
> On Tue, Nov 22, 2011 at 18:15, Matthew Garrett <mjg@xxxxxxxxxx> 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@xxxxxxxxxxxxx
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