Make sure that the request has been submitted to HW before we begin our
wait. This reduces our reliance on the semaphore yield interrupt driving
the preemption request.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201222113536.3775-2-chris@chris-wilson.co.uk