[Mesa-dev] [PATCH 1/2] gallium: add PIPE_FLUSH_DEFERRED

[Marek Olšák]

On Mon, Jul 18, 2016 at 2:25 PM, Rob Clark <robdclark at gmail.com> wrote:
> On Mon, Jul 18, 2016 at 8:16 AM, Marek Olšák <maraeo at gmail.com> wrote:
>> From: Marek Olšák <marek.olsak at amd.com>
>>
>> There are 2 uses:
>> - Asynchronous flushing for multithreaded drivers.
>> - Return a fence without flushing (mid-command-buffer fence). The driver
>>   can defer flushing until fence_finish is called.
>
> This should also be useful to me when I get a chance to rebase the
> gallium bits of the egl fence-fd patchset.  I guess the one question
> is what the behaviour is in screen->fence_finish().  I think I have a
> solution for that in freedreno (if I end up going the
> flush-from-u_queue route, since I'd end up with enough locking to
> flush without a ctx), although maybe that isn't the most general
> solution for other drivers.  I wonder if we should add an optional
> pipe_context ptr to fence_finish() for the cases when there is a
> context bound?
>
> Either way, I guess we need a bit more documentation about that.  With
> that resolved, r-b

The behavior of fence_finish isn't changed. The only side effect can
be that fence_finish will wait a little longer. No guidance is given
as to how drivers should implement fence_finish with deferred flushes.
If some drivers can't do deferred flushes safely, they should just
ignore the flag.

Marek