[Intel-gfx] [PATCH 3/3] drm/vgem: Attach sw fences to exported vGEM dma-buf (ioctl)

[Chris Wilson]

On Tue, Jul 12, 2016 at 12:44:17PM +0200, Daniel Vetter wrote:
> On Mon, Jul 11, 2016 at 04:24:45PM +0100, Chris Wilson wrote:
> > That doesn't fit the out-of-order unbound nature of the interface. The
> > interface is just a collection of fences that userspace associates with
> > the buffer that it may signal at any time. (Having no strict timeline is
> > an advantage!)
> 
> Fences on the same timeline are supposed to be signalled in-order. If you
> want full out-of-order fences then you need to grab a new timeline number
> for each one. Drivers can and do merge fences on the same timeline and
> just carry the one with the largest seqno around.

Ugh. Timelines simply don't mean anything everywhere - a very leaky
abstration.

Nevertheless, a fence_context per vgem_fence would do the trick.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre