On Thu, Jun 25, 2020 at 3:23 PM Lionel Landwerlin <lionel.g.landwerlin@xxxxxxxxx> wrote: > > 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. I asked Christian to document why timeline works like this, but I can't find it in the kerneldoc right now. If it's missing I think we should fix that and add the explanation, iirc it was around gpu reset creating too much havoc otherwise. -Daniel > > > -Lionel > > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/intel-gfx -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
