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

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Date:	Sat, 19 Nov 2011 07:25:09 -0200
From:	Eugeni Dodonov <eugeni@...onov.net>
To:	Keith Packard <keithp@...thp.com>
Cc:	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 Sat, Nov 19, 2011 at 04:41, Keith Packard <keithp@...thp.com> wrote:
>
> +static bool intel_enable_rc6(struct drm_device *dev)
> +{
> +       if (i915_enable_rc6 >= 0)
> +               return i915_enable_rc6;
> +       if (INTEL_INFO(dev)->gen >= 7)
> +               return 1;
> +#ifdef CONFIG_INTEL_IOMMU
> +       /*
> +        * 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;
> +#endif
> +       return 0;
> +}

Just one question I caught on 2nd read. Shouldn't we have #else within
this #ifdef block, to return 1? Otherwise, if CONFIG_INTEL_IOMMU is
not defined, we'll always disable rc6.

Or we just always intend to disable rc6 in case CONFIG_INTEL_IOMMU is not there?

--
Eugeni Dodonov
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