[Bug 85861] backlight control doesn't work on Lenovo t440p after upgrading to 3.17 [bisected]

[bugzilla-daemon at bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=85861

--- Comment #13 from Tommi Kyntola <kynde at ts.ray.fi> ---
Applied that to 3.17.1 and it works, too, _but_ a little differently wrt. 0%

kernel                      FN-<brightness>
3.1x.y vanilla              works, 0% is very dark
3.16.4 vanilla              works, 0% is black
3.17.1 vanilla              doesn't work
3.17.1 reverted 6dda730     works, 0% is black
3.17.1 applied #9 patch     works, 0% is black
3.17.1 applied fff95501     works, 0% is very dark

I can't remember when you guys introduced the 0% is black, but it was some
weeks/months ago. I can check up on that if you like, but I reckon you already
know when that happened.

Although the totally black 0% it initially struck me as odd I learned to
actually like that better than the "very very dark" 0%. I suppose that's a
matter of opinion and at least I now know where to mess around if I indeed want
a black 0%.


As a side note, I think the userland could benefit from non-linear scaling.
Changes in upper end of the spectrum seem a lot less to a human eye than in the
darker end of the spectrum. I rarely find any benefit in going from 100% to
80%, but often find myself not finding quite enough resolution around 10% to
20% or there abouts. We added quadratic scaling to resolve similar shortcomings
in audio control in our gaming machines. But that is certainly userland stuff,
and I'm not even sure if there's already some mechanisms already in place.

-- 
You are receiving this mail because:
You are on the CC list for the bug.
You are the assignee for the bug.