Re: [PATCH] drm/i915: Android sync points for i915 v2

[Jesse Barnes <jbarnes@virtuousgeek.org>]

On Tue, 05 Aug 2014 10:09:56 +0200
Maarten Lankhorst <maarten.lankhorst@canonical.com> wrote:

> op 05-08-14 01:18, Jesse Barnes schreef:
> > Expose an ioctl to create Android fences based on the Android sync point
> > infrastructure (which in turn is based on DMA-buf fences).  Just a
> > sketch at this point, no testing has been done.
> >
> > There are a couple of goals here:
> >   1) allow applications and libraries to create fences without an
> >      associated buffer
> >   2) re-use a common API so userspace doesn't have to impedance mismatch
> >      between different driver implementations too much
> >   3) allow applications and libraries to use explicit synchronization if
> >      they choose by exposing fences directly
> >
> > v2: use struct fence directly using Maarten's new interface
> 
> > diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> > index d604f4f..6eb119e 100644
> > --- a/drivers/gpu/drm/i915/i915_drv.h
> > +++ b/drivers/gpu/drm/i915/i915_drv.h
> > @@ -1388,6 +1388,8 @@ struct i915_frontbuffer_tracking {
> >  	unsigned flip_bits;
> >  };
> >  
> > +struct i915_sync_timeline;
> > +
> >  struct drm_i915_private {
> >  	struct drm_device *dev;
> >  	struct kmem_cache *slab;
> > @@ -1422,6 +1424,8 @@ struct drm_i915_private {
> >  	struct drm_i915_gem_object *semaphore_obj;
> >  	uint32_t last_seqno, next_seqno;
> >  
> > +	struct i915_sync_timeline *sync_tl[I915_NUM_RINGS];
> > +
> >  	drm_dma_handle_t *status_page_dmah;
> >  	struct resource mch_res;
> >  
> Leftover remnant?

Oops, yeah.  I still need to add a way to request a fence on a specific
ring, and that ties into our context API, so that's still open.  But I
definitely don't want a sync timeline here with this approach.

> I think you should rebase on top of Chris' seqno/request stuff like you said in TODO, it would reduce the patch to just the ioctl. ;-)

I need to check if it landed yet, but yes it will make things even
simpler.

-- 
Jesse Barnes, Intel Open Source Technology Center