announce: alternate power management

Mikus Grinbergs mikus at
Sat Mar 14 00:34:29 EDT 2009

> configurable timeouts for screen dim and sleep.  the dim
> level is configurable.

My XO systems are plugged in to the AC, so I normally leave them 
running 24/7.  But in the middle of the night if I happen to walk 
by, I notice if they are acting as "light sources".  Two concerns 
(for which I don't know whether doing anything is feasible):

  -  Rawhide.  AFAIK there currently is no dimming support at all. 
I either have to power off such an XO overnight, or have to close 
the lid while the backlight is still lit.  It would be useful if 
rawhide supported dimming/shutting_off the screen when no one is 
looking at it (irrespective of whether the CPU is doing work or not).

  -  Suspend.  It was functioning well only with Joyride - but I 
hope it gets implemented other places as well.  The problem is - the 
CPU may suspend because it is idle (and partly dim the screen), but 
the user may still continue looking at that screen (in color mode) 
while the XO is suspended.  After a decent interval at half-bright, 
it is reasonable to assume the user has "seen enough", and the 
screen could now be dimmed all the way off.  BUT since the system is 
"sleeping", the current implementation has no way to "wake up" the 
system just so it can execute 'screen dim' instructions.  The result 
is that if I don't intervene at the keyboard, my suspended (Joyride) 
XO's screen remains half-bright throughout the night.  I think it 
counter-productive to suspend the rest of the system (to save 
power!) when no one is using it, but to leave the screen lit (still 
drawing power!) once it can be presumed no one is using it any more.

> different power behavior when in ebook mode (though detection
> may be unreliable -- i think the ebook switch suffers from
> some issues we previously noticed with the lid switch).

What issues ?  I thought the lid switch could be fooled by people 
with magnets - but that an actual "shut" would always be recognized 
as being a "shut" (and a failure to recognize an "open" could be 
overcome by momentarily pressing the power button).


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