[Intel-gfx] [PATCH 2/3] drm/i915: add syncobj timeline support

[Lionel Landwerlin]

On 31/07/2020 17:32, Chris Wilson wrote:
> Quoting Lionel Landwerlin (2020-07-31 14:45:52)
>> Introduces a new parameters to execbuf so that we can specify syncobj
>> handles as well as timeline points.
>>
>> v2: Reuse i915_user_extension_fn
>>
>> v3: Check that the chained extension is only present once (Chris)
>>
>> v4: Check that dma_fence_chain_find_seqno returns a non NULL fence (Lionel)
>>
>> v5: Use BIT_ULL (Chris)
>>
>> v6: Fix issue with already signaled timeline points,
>>      dma_fence_chain_find_seqno() setting fence to NULL (Chris)
>>
>> v7: Report ENOENT with invalid syncobj handle (Lionel)
>>
>> v8: Check for out of order timeline point insertion (Chris)
>>
>> v9: After explanations on
>>      https://lists.freedesktop.org/archives/dri-devel/2019-August/229287.html
>>      drop the ordering check from v8 (Lionel)
>>
>> v10: Set first extension enum item to 1 (Jason)
> The other unaddressed issue here is that we do not need to arbitrarily
> limit the caller to only a single extension. The code to handle multiple
> invocations is actually smaller...
> -Chris

You mean an application could send multiple 
DRM_I915_GEM_EXECBUFFER_EXT_TIMELINE_FENCES items in the chain of 
extensions?

That's somewhat different than how the current fences are handled.

If other extension want to support that, that's up to them.

We don't have any use for multiple arrays of timeline fences for a given 
execbuf in our userspace driver.


-Lionel