[Intel-gfx] [PATCH 1/2] drm/i915: Android sync points for i915 v2

[Chris Wilson]

On Wed, Sep 03, 2014 at 07:41:34PM +0300, Ville Syrjälä wrote:
> Also looks quite a bit like my ring notify doohicky from:
> http://lists.freedesktop.org/archives/intel-gfx/2014-June/047623.html

Indeed, fences look similar :)
 
> Except I kept the list in the driver so you would need to do only one
> get_seqno() per irq. Also if the list would be sorted (which it wasn't
> in my patch) it would prevent signalling the fences out of order. But
> maybe that's not really a problem for anyone.
> 
> Hmm, so if the out of order thing isn't a problem maybe use the wait
> queue still but replace the wake_up() with __wake_up() so that the seqno
> can be passed in as the key. That's assuming people care about
> optimizing the seqno reads.

No, we don't care about plain seqno reads - they're a cached read.

But having a kthread dedicated to internal fence signalling makes sense
if we have more than just mmioflips waiting. At the moment, I am quite
happy with using one of the system kthread pool for just mmioflips.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre