[Intel-gfx] [RFC v2] drm/i915: Android native sync support

[Chris Wilson]

On Fri, Jan 23, 2015 at 11:13:14AM +0000, Tvrtko Ursulin wrote:
> From: Jesse Barnes <jbarnes at virtuousgeek.org>
> 
> Add Android native sync support with fences exported as file descriptors via
> the execbuf ioctl (rsvd2 field is used).
> 
> This is a continuation of Jesse Barnes's previous work, squashed to arrive at
> the final destination, cleaned up, with some fixes and preliminary light
> testing.
> 
> GEM requests are extended with fence structures which are associated with
> Android sync fences exported to user space via file descriptors. Fences which
> are waited upon, and while exported to userspace, are referenced and added to
> the irq_queue so they are signalled when requests are completed. There is no
> overhead apart from the where fences are not requested.
> 
> Based on patches by Jesse Barnes:
>    drm/i915: Android sync points for i915 v3
>    drm/i915: add fences to the request struct
>    drm/i915: sync fence fixes/updates
> 
> To do:
>    * Extend driver data with context id / ring id (TBD).
> 
> v2:
>    * Code review comments. (Chris Wilson)
>    * ring->add_request() was a wrong thing to call - rebase on top of John
>      Harrison's (drm/i915: Early alloc request) to ensure correct request is
>      present before creating a fence.
>    * Take a request reference from signalling path as well to ensure request
>      sticks around while fence is on the request completion wait queue.

Ok, in this arrangement, attaching a fence to the execbuf is rather meh
as it is just a special cased version of attaching a fence to a bo.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre