Re: [RFC] ledtrig-dither: A Poor man's adjustable LED brightness.

[Pavel Machek <pavel@ucw.cz>]

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On Wed 2017-08-16 00:55:04, Paulo Costa wrote:
> > Hmm. Can we simply use blinking trigger to do that?
> 
> To some extent...
> 
> If you just want to have 50% brightness, set timeon=1, timeoff=1 and
> you are done.
> 
> But, accurately seting the brightness to weird numbers is harder.
> E.g., To get 37% brightness your only chance is to set timeon=37,
> timeoff=63 (Or multiples of it).
> 
> The larger delay causes very visible flickering, which sucks.

Well, to set 37% brightness you just set timeon=1 timeoff=2 ;-).

> This trigger uses error propagation to continously adjusts the delay,
> getting a higher blink frequency and accurate average brightness.
> 
> E.g., For 37% it will alternate between 33% (timeon=1,timeoff=2) and
> 50% (timeon=1,timeoff=1)

Hmm, ok, clever.

> Unfortunately, it doesn't really help when the brightness is near 0%
> or near 100%.
> E.g., for 1% brightness, this trigger it is equivalent to
> timeon=1,timeoff=99 -- Flickering is very visible.

Hmm. You could do led=on, udelay(100), led=off. Do that 100 times a
second, and I believe you'll get quite nice low levels.

Now... nice hack. Probably can be improved. But is it suitable for
mainline?

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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