Daniel Vetter authored Dec 16, 2015 and Chris Wilson committed Dec 16, 2015

So there's 3 competing proposals for what wait_ioctl should do wrt
-EIO:

- return -EIO when the gpu is wedged. Not terribly useful for
  userspace since it might race with a hang and then there's no
  guarantee that a subsequent execbuf won't end up in an -EIO.
  Terminally wedge really can only be reliably signalled at execbuf
  time, and userspace needs to cope with that (or decide not to
  bother).

- EIO for any obj that suffered from a reset. This means big internal
  reorginazation in the kernel since currently we track reset stats
  per-ctx and not on the obj. That's also what arb robustness wants.
  We could do this, but this feels like new ABI territory with the
  usual userspace requirements and high hurdles.

- No -EIO at all. Consistent with set_domain_ioctl and simplest to
  implement. Which is what this patch does.

We can always opt to change this later on if there's a real need.

To make the test really exercise this do a full wedged gpu hang, to
make sure -EIO doesn't leak out at all.

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>