[Intel-gfx] gpu outputs slave and cache flushing

[Dave Airlie]

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.

Dave.