On 25/06/2020 16:18, Chris Wilson wrote:
Quoting Lionel Landwerlin (2020-06-25 13:34:43)
There was probably a misunderstand on how the dma-fence-chain is
supposed to work or what dma_fence_chain_find_seqno() is supposed to
return.
dma_fence_chain_find_seqno() is here to give us the fence to wait upon
for a particular point in the timeline. The timeline progresses only
when all the points prior to a given number have completed.
Hmm, the question was what point is it supposed to wait for.
For the simple chain of [1, 3], does 1 being signaled imply that all
points up to 3 are signaled, or does 3 not being signaled imply that all
points after 1 are not. If that's mentioned already somewhere, my bad.
If not, could you put the answer somewhere.
-Chris
In [1, 3], if 1 is signaled, the timeline value is 1. And find_seqno(2)
should return NULL.
In the out_of_order selftest the chain was [1, 2, 3], 2 was signaled and
the test was expecting no fence to be returned by find_seqno(2).
But we still have to wait on 1 to complete before find_seqno(2) can
return NULL (as in you don't have to wait on anything).
Hope that answer the question.
-Lionel
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