[Intel-gfx] [PATCH] allocate & enable MCHBAR if needed

Chris Wilson chris at chris-wilson.co.uk
Thu Feb 12 12:38:02 CET 2009

On Wed, 2009-02-11 at 17:54 -0800, Jesse Barnes wrote:
> I noticed on my Eee 901 that the i915 DRM driver wasn't reading the MCHBAR reg
> at startup time, and so it would disable tiling.  For decent performance,
> especially on an Eee-like platform, tiling is a must.  So I put this patch
> together to allocate MCHBAR space and enable it if necessary.
> In combination with the pre-965 tiling patches in the tree now, you should see
> a big performance improvement if you have an affected machine.
> (Note to Eric: don't merge this until someone else confirms it works for them
> too.)

No joy, I'm afraid. This patch fails to enable tiling on my el cheapo
eee 700. Just to reaffirm with the previous patch I get a performance
boost of around a factor of 20x over this version.
(And /proc/dri/0/i915_gem_fence indeed reports no tiling). I noticed
that wasn't any debugging output; is there anything I can do to help?

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