lid wakeups

Paul Fox pgf at
Mon Jun 22 09:38:20 EDT 2009

[ thread moved from techteam list ]

richard wrote:
 > John Watlington wrote:
 > >paul wrote:
 > >> when i compared to gen1.5, realized there was no lid connection
 > >> at all.  it'd be nice for the screen -- the backlight at least --
 > >> to reliably shut off when the lid is closed.
 > > 
 > > Hmm.  I see your point.  We should fix this in software, as both the
 > > backlight power and display power are controlled through the DCON.
 > > The EC could remove power from the DCON, but that prevents rapid
 > > redisplay on lid open...   This thread should move to devel.
 > On boot OFW inits the DCON from dead cold in fractions of a second.
 > The kernel already does this as well. Turn a Gen 1 on and let it sit for 
 > 20 minutes to let the DPMS screen saver kick on then press a key.  The 
 > turn on is virtually instant.  Thats the kernel doing a full DCON init. 

right -- my point was not about speed at all.  the issue is that
if we're suspended with dcon and/or backlight on, when the lid is
closed, we don't have a reliable way of waking up to turn the
screen/backlight off.

but what thinking about this has really made me realize is that i
don't fully understand how lid wakeups work, even for the
lid-open case that we do support.  it seems that EC involvement
is required, even though it's clear from the code in olpc-pm.c
(and the history in #5703) that the geode gpio connections are
key to the process.  are there cases where the geode isn't awake
enough to force a wakeup by itself?

(i'm talking exclusively about gen1 here, btw.)

 paul fox, pgf at

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