[Intel-gfx] [CI 20/21] drm/i915: Remove unsafe i915.enable_rc6

[Chris Wilson]

Quoting Matt Turner (2017-11-21 01:04:28)
> On Sun, Nov 19, 2017 at 6:32 AM, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> > It has been many years since the last confirmed sighting (and fix) of an
> > RC6 related bug (usually a system hang). Remove the parameter to stop
> > users from setting dangerous values, as they often set it during triage
> > and end up disabling the entire runtime pm instead (the option is not a
> > fine scalpel!).
> 
> This makes a lot of sense, except for the fact that the next patch
> enables RC6 on Ironlake...

It's hard to test otherwise... How much was our own fail? FBC is still
disabled on ilk because we couldn't get the wm programming right, maybe
that now works after the umpteen rewrites... (But ilk fbc is still
likely a net loss in powersaving!)
-Chris