[Intel-gfx] [PATCH] agp/intel: Fix the pre-9xx chipset flush.

Eric Anholt eric at anholt.net
Fri Sep 11 20:37:58 CEST 2009

On Fri, 2009-09-11 at 08:34 +0200, Brice Goglin wrote:
> Eric Anholt wrote:
> > The chipset flush was on the right track -- hitting the right amount of
> > memory, and it appears to be the only way to flush on these chipsets, but the
> > flush page was mapped uncached.  As a result, the writes trying to clear the
> > writeback cache ended up bypassing the cache, and not flushing anything!  The
> > wbinvd would flush out other writeback data and often cause the data we wanted
> > to get flushed, but not always.  By removing the setting of the page to UC
> > and instead just clflushing the data we write to try to flush it, we get the
> > desired behavior with no wbinvd. 
> >   
> This helps a lot, thanks Eric. I've been running various things under
> metacity and compiz during the last 10mn without problems while X would
> usually hang after 10s. But I needed the below patch to build the
> intel-agp driver as a module.


Eric Anholt
eric at anholt.net                         eric.anholt at intel.com

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