[Intel-gfx] [PATCH i-g-t] lib/igt_pm: Restore runtime pm state on test exit

[Chris Wilson]

Quoting Tvrtko Ursulin (2018-02-28 11:38:01)
> 
> On 28/02/2018 11:12, Chris Wilson wrote:
> > Quoting Tvrtko Ursulin (2018-02-28 11:08:29)
> >> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> >>
> >> Some tests (the ones which call igt_setup_runtime_pm and
> >> igt_pm_enable_audio_runtime_pm) change default system configuration and
> >> never restore it.
> >>
> >> The configured runtime suspend is aggressive and may influence behaviour
> >> of subsequent tests, so it is better to restore to previous values on test
> >> exit.
> >>
> >> This way system behaviour, with regards to a random sequence of executed
> >> tests, will be more consistent from one run to another.
> > 
> > Otoh, if behaviour changes in subsequent tests, we likely have a lack of
> > testing :(
> 
> Yeah, and I am not saying it does - haven't spotted anything like that, 
> just that it leaves the auto-suspend with zero delay afterwards, 
> compared to otherwise default 10s.
> 
> Maybe it is good for coverage, even with the downside of randomness 
> considering shard runs, or maybe it needs to be more explicit.

I actually thought (or at least picked up the idea) we enabled 0
autosuspend delay throughout igt. And that it's only because most of time
we have a display connected that prevents rpm madness.
-Chris