[PATCH] drm/i915: Before pageflip, also wait for shared dmabuf fences.

[Michel Dänzer]

On 11/10/16 09:04 PM, Christian König wrote:
> Am 11.10.2016 um 05:58 schrieb Michel Dänzer:
>> On 07/10/16 09:34 PM, Mike Lothian wrote:
>>> This has discussion has gone a little quiet
>>>
>>> Was there any agreement about what needed doing to get this working
>>> for i965/amdgpu?
>> Christian, do you see anything which could prevent the solution I
>> outlined from working?
> 
> I thought about that approach as well, but unfortunately it also has a
> couple of downsides. Especially keeping the exclusive fence set while we
> actually don't need it isn't really clean either.

I was wondering if it's possible to have a singleton pseudo exclusive
fence which is used for all BOs. That might keep the overhead acceptably
low.


> I'm currently a bit busy with other tasks and so put Nayan on a road to
> get a bit into the kernel driver (he asked for that anyway).
> 
> Implementing the simple workaround to sync when we export the DMA-buf
> should be something like 20 lines of code and fortunately Nayan has an
> I+A system and so can actually test it.
> 
> If it turns out to be more problematic or somebody really starts to need
> it I'm going to hack on that myself a bit more.

If you mean only syncing when a DMA-buf is exported, that's not enough,
as I explained before. The BOs being shared are long-lived, and
synchronization between GPUs is required for every command stream
submission.


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer