lid wakeups

Richard A. Smith richard at
Tue Jun 23 11:04:02 EDT 2009

Paul Fox wrote:

> 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.)

The  EC is involved because the EC controls the DCON power, its just not 
in charge.  You have to drop power to the DCON because the DCON's "low 
power" mode does not save you much.  So the kernel tells the EC to turn 
the DCON on or off.

On a B1 the lid signal was connected to both the geode and the EC but 
when we moved things around in later revs it ended up only run to the 
geode. (We needed EC IO)  The geode lid events turned out to be 
unreliable (for a never fully understood reason) and we ended up with 
the logic that ohm does now.

in Gen 1.5 we expect the gpio wakeups to work correctly (which is 
someting we need to test soon) and lid wakeups won't be so messy.
Richard Smith  <richard at>
One Laptop Per Child

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