Messages in this thread | | | Date | Wed, 12 Jun 2019 11:54:13 +0200 | From | Pavel Machek <> | Subject | Re: [PATCH v3 3/4] backlight: pwm_bl: compute brightness of LED linearly to human eye. |
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On Tue 2019-06-11 15:30:19, Matthias Kaehlcke wrote: > On Tue, Jun 11, 2019 at 09:55:30AM -0700, Brian Norris wrote: > > On Tue, Jun 11, 2019 at 3:49 AM Daniel Thompson > > <daniel.thompson@linaro.org> wrote: > > > This is a long standing flaw in the backlight interfaces. AFAIK generic > > > userspaces end up with a (flawed) heuristic. > > > > Bingo! Would be nice if we could start to fix this long-standing flaw. > > Agreed! > > How could a fix look like, a sysfs attribute? Would a boolean value > like 'logarithmic_scale' or 'linear_scale' be enough or could more > granularity be needed?
I'd expect attribute "scale" with values "linear" or "logarithmic".
> The new attribute could be optional (it only exists if explicitly > specified by the driver) or be set to a default based on a heuristic > if not specified and be 'fixed' on a case by case basis. The latter > might violate "don't break userspace" though, so I'm not sure it's a > good idea.
I'd do it only when we explicitely know. We don't want it to be buggy.
And I guess we should decide what interface we really want? (Linear? Logarithmic?) And make new drivers do that.
Best regards, Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html [unhandled content-type:application/pgp-signature] | |