linux-kernel - Re: [RFC 1/8] dma-buf/fence: add fence

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Date:	Fri, 15 Apr 2016 11:29:34 -0700
From:	Gustavo Padovan <gustavo@...ovan.org>
To:	Daniel Vetter <daniel@...ll.ch>
Cc:	Christian König <christian.koenig@....com>,
	dri-devel <dri-devel@...ts.freedesktop.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Daniel Stone <daniels@...labora.com>,
	Arve Hjønnevåg <arve@...roid.com>,
	Riley Andrews <riandrews@...roid.com>,
	Rob Clark <robdclark@...il.com>,
	Greg Hackmann <ghackmann@...gle.com>,
	John Harrison <John.C.Harrison@...el.com>,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	Sean Paul <seanpaul@...gle.com>,
	Stéphane Marchesin <marcheu@...gle.com>,
	m.chehab@...sung.com,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Gustavo Padovan <gustavo.padovan@...labora.co.uk>
Subject: Re: [RFC 1/8] dma-buf/fence: add fence_collection fences

2016-04-15 Daniel Vetter <daniel@...ll.ch>:

> On Fri, Apr 15, 2016 at 11:03 AM, Christian König
> <christian.koenig@....com> wrote:
> > Might be that how amdgpu uses the fence context and sequence number is a bit
> > questionable, but this will completely break it.
> 
> You mean it tries to qualesce fences in the same context down to just
> the last one? That's how it's supposed to be done, and
> fence_collections do break this somewhat. Without fixing up
> fence_is_later and friends. Sounds like amdgpu is a good use case to
> make sure the changes in semantics in these functions result in
> sensible code. In a way a fence_collection is a fence where the
> timeline never matches with any other timeline (since it's a
> combiation).
> 
> And yeah I think fence_collection should probably compress down the
> fences to 1 per timeline. But then that's just an implementation
> detail we can fix later on.

You mean asking for a new context for every collection?

	Gustavo