Re: [PATCH] dma-buf/dma-fence: Mark two callbacks as deprecated

[Philipp Stanner <phasta@mailbox.org>]

On Fri, 2026-09-25 at 10:21 +0200, Christian König wrote:
> Some problems like the locking design are still WIP, but we are
> slowly moving towards that.

The question will be whether we can reach common ground with that one.

> 
> But some problems like parts of the dma_fence uAPI are unfixable
> without time travel.

I would be especially interested in learning about who the party is
that apparently is spinning on dma_fence_is_signaled(), supposedly
preventing us from getting the memory ordering right.

Also learning more about the users that definitely *need* ops-
>signaled() and ops->enable_signaling() would be interesting. drm_sched
users cannot make use of these, since the sched-fence does not pass the
request through to the hardware fence.

So who are the users? Parties like Nouveau implement these callbacks,
but it's not clear whether they actually need them.

(btw, funnily enough, with the Rust-fence design we finally have the
ability to fully support all callbacks with or without a scheduler,
since the need for an intermediate fence disappeared)


P.