[Intel-gfx] [PATCH i-g-t] tests/kms_busy: Only test agains one engine

[Chris Wilson]

Quoting Daniel Vetter (2017-08-03 13:05:29)
> Back when we used cs flips it made sense to go through different
> engines, since a buffer busy on an engine that we couldnt' use for
> cs flipping ended up in different paths.
> 
> But with atomic we use a worker for all flips, and going through the
> combinatorial growth of engines just wastes precious machine time.
> More so the more modern the platform is.

Then test against all engines simultaneously.

> Of course gem tests should still do some diagonal testing across all
> engines, but the kms side can afford to be a bit cheaper.

kms has a separate waiting interface, it would be prudent to not assume
that coverage elsewhere gives coverage of kms. Note also that kms has a
number of special paths for domain handling which require care and
attention.
-Chris