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Subject: Re: TTM placement & caching issue/questions
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Jerome Glisse <j.glisse@gmail.com>
Date: Thu, 04 Sep 2014 15:23:05 +1000
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Cc: Alex Deucher <alexander.deucher@amd.com>, linuxppc-dev@ozlabs.org,
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On Wed, 2014-09-03 at 22:36 -0400, Jerome Glisse wrote:
> On Wed, Sep 03, 2014 at 10:31:18PM -0400, Jerome Glisse wrote:
> > On Thu, Sep 04, 2014 at 12:25:23PM +1000, Benjamin Herrenschmidt wrote:
> > > On Wed, 2014-09-03 at 22:07 -0400, Jerome Glisse wrote:
> > > 
> > > > So in the meantime the attached patch should work, it just silently ignore
> > > > the caching attribute request on non x86 instead of pretending that things
> > > > are setup as expected and then latter the radeon ou nouveau hw unsetting
> > > > the snoop bit.
> > > > 
> > > > It's not tested but i think it should work.
> > > 
> > > I'm still getting placements with !CACHED going from bo_memcpy in
> > > ttm_io_prot() though ... I'm looking at filtering the placement
> > > attributes instead.
> > > 
> > > Ben.
> > 
> > Ok so this one should do the trick.
> 
> Ok final version ... famous last word.

Minus a couple of obvious typos that prevent if from building, it seems
to do the trick for me with the AST driver, no more bad mappings.

I'll still send a patch that catches the incorrect mapping attempts
inside ttm_io_prot() and warns to help future debugging and avoid
"random" behaviour. (I need to fix other things in the powerpc code
in there anyway).

Cheers,
Ben.