[Intel-gfx] gpu outputs slave and cache flushing

[Chris Wilson]

On Tue, Jul 30, 2013 at 03:04:22PM +1000, Dave Airlie wrote:
> Hey,
> 
> so I put a patch into intel driver a while ago to avoid doing a bo
> flush using map/unmap for output slave device if the kernel has vmap
> flushing
> 
> However on reflection I realised this only works for CPU accessing
> devices like UDL but doesn't work for GPU accessing devices like
> nouveau/radeon,
> 
> Going forward I'm sure we'll eventually get GPU sync via Maarten's
> patches but I'm thinking I should revert this change in the intel
> driver for now,
> so reverse optimus can work properly
> 
> Anyone got any ideas for a better plan going forward, maybe a stop gap
> before Maartens patches.

I don't think it is possible to w/a this in userspace, so let's blame
Daniel^WBen for this mess and cheer on our knight in shining armour.
Go Maarten! But we need to be sure there is a similar synchronisation
point for CPU access to a foriegn dma-buf.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre