On 01/23/2015 11:27 AM, Chris Wilson wrote:
On Fri, Jan 23, 2015 at 11:13:14AM +0000, Tvrtko Ursulin wrote:
From: Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx>
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.
Better meh than "no"! :D
My understanding is this is what people want, with the future input
fence extension (scheduler).
Anyway.. v2 is broken since it unreferences requests without holding the
mutex, more so from irq context so I need to rework that a bit.
Regards,
Tvrtko
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