On Tue, 06 Sep 2011 15:11:12 +0200, Philipp Klaus Krause <pkk@spth.de> wrote:

> Here's the output from git-bisect:
> 
> d74362c9e45689d8d7e3d4bcf6681c4358ef4f2e is the first bad commit
> commit d74362c9e45689d8d7e3d4bcf6681c4358ef4f2e
> Author: Keith Packard <keithp@keithp.com>
> Date:   Thu Jul 28 14:47:14 2011 -0700
> 
>     drm/i915: Flush other plane register writes
> 
>     Writes to the plane control register are buffered in the chip until a
>     write to the DSPADDR (pre-965) or DSPSURF (post-965) register
>     occurs.

Makes me wonder if this is some interaction between page flipping and
frame buffer compression. Could you try turning it off with the
following kernel command line parameter?

        i915.i915_enable_fbc=0

-- 
keith.packard@intel.com