[Intel-gfx] [CI] drm/i915: Avoid sleeping inside per-engine reset

[Chris Wilson]

Quoting Chris Wilson (2018-03-28 23:30:56)
> Only sleep and repeat when asked for a full device reset (ALL_ENGINES)
> and avoid using sleeping waits when asked for a per-engine reset. The
> goal is to be able to use a per-engine reset from hardirq/softirq/timer
> context. A consequence is that our individual wait timeouts are a
> thousand times shorter, on the order of a hundred microseconds rather
> than hundreds of millisecond. This may make hitting the timeouts more
> common, but hopefully the fallover to the full-device reset will be
> sufficient to pick up the pieces.
> 
> Note, that the sleeps inside older gen (pre-gen8) have been left as they
> are only used in full device reset mode.

I'm not planning on rushing this one, but I do need to bounce it off the
HW a few times to see if we are opening a can of worms with the reduced
timeouts.
-Chris