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Date:   Thu, 8 Aug 2019 14:02:52 +0200
From:   Daniel Vetter <daniel@ffwll.ch>
To:     Gerd Hoffmann <kraxel@redhat.com>
Cc:     "Koenig, Christian" <Christian.Koenig@amd.com>,
        David Airlie <airlied@linux.ie>,
        "Huang, Ray" <Ray.Huang@amd.com>,
        "tzimmermann@suse.de" <tzimmermann@suse.de>,
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        open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 2/8] ttm: turn ttm_bo_device.vma_manager into a pointer
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On Thu, Aug 08, 2019 at 12:35:21PM +0200, Gerd Hoffmann wrote:
> On Thu, Aug 08, 2019 at 09:48:49AM +0000, Koenig, Christian wrote:
> > Am 08.08.19 um 11:36 schrieb Gerd Hoffmann:
> > > Rename the embedded struct vma_offset_manager, it is named _vma_manager
> > > now.  ttm_bo_device.vma_manager is a pointer now, pointing to the
> > > embedded ttm_bo_device._vma_manager by default.
> > >
> > > Add ttm_bo_device_init_with_vma_manager() function which allows to
> > > initialize ttm with a different vma manager.
> > 
> > Can't we go down the route of completely removing the vma_manager from 
> > TTM? ttm_bo_mmap() would get the BO as parameter instead.
> 
> It surely makes sense to target that.  This patch can be a first step
> into that direction.  It allows gem and ttm to use the same
> vma_offset_manager (see patch #3), which in turn makes various gem
> functions work on ttm objects (see patch #4 for vram helpers).

+1 on cleaning this up for good, at least long-term ...

> > That would also make the verify_access callback completely superfluous 
> > and looks like a good step into the right direction of de-midlayering.
> 
> Hmm, right, noticed that too while working on another patch series.
> Guess I'll try to merge those two and see where I end up ...

... but if it gets too invasive I'd vote for incremental changes. Even if
we completely rip out the vma/mmap lookup stuff from ttm, we still need to
keep a copy somewhere for vmwgfx. Or would the evil plan be the vmwgfx
would use the gem mmap helpers too?
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch