automatic backlight control

Paul Fox pgf at
Mon Nov 21 16:18:12 EST 2011

forster at wrote:
 > The shift from colour to monochrome is noticable and would be annoying if it 
 > happened a lot, for example as clouds pass, trees and people move.
 > If the hysterisis, the difference between cutin and cutout brightness is large, 
 > the change in mode will happen a lot less frequently and not be annoying.
 > I would like to try it switching automatically to monochrome but with large 
 > hysterisis.
 > I'll wait to try OS12

you may be in a better position to play with this, geographically
speaking, than i am -- we're running low on sunlight these days.

the hysteresis is currently hard-coded in powerd -- you'll find it in
the function ambient_adjust_init().  it only gets set once, though, so
after powerd starts, you can change the limits directly and they
should take effect immediately.

additionally, to cause auto-monochrome to happen, uncomment the
obvious lines at the end of set_brightness() and brightness_ramp().


 > Tony
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 > Devel at

 paul fox, pgf at

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