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Subject: Re: [PATCH v3 2/8] ttm: turn ttm_bo_device.vma_manager into a pointer
To:     Gerd Hoffmann <kraxel@redhat.com>,
        "Koenig, Christian" <Christian.Koenig@amd.com>,
        David Airlie <airlied@linux.ie>,
        "Huang, Ray" <Ray.Huang@amd.com>,
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From:   =?UTF-8?Q?Thomas_Hellstr=c3=b6m_=28VMware=29?= 
        <thomas@shipmail.org>
Organization: VMware Inc.
Message-ID: <36145412-3c31-e635-1e8b-b42439811742@shipmail.org>
Date:   Thu, 8 Aug 2019 14:43:17 +0200
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On 8/8/19 2:02 PM, Daniel Vetter wrote:
> 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?

I don't think it would be too invasive. We could simply move 
ttm_bo_vm_lookup into a vmw_mmap.

/Thomas


> -Daniel