My Gta02s wont charge / chgena = 0 by default

[Werner Almesberger]

I wrote:
> Now, on to strangling the Glamo ...

Here we go:
http://svn.openmoko.org/developers/werner/meas/chg/choke-glamo/out.ps

The next and for now final step is to enter CPU IDLE in wait_for_power
instead of busy-looping and polling the PMU like crazy:

http://svn.openmoko.org/developers/werner/meas/chg/cpu-idle/out.ps

(Note: the directories with out.ps also contain the raw data, a more
detailed description of the experiments, and sometimes other related
material.)

So the current drawn in wait_for_power is, when the LED is off:

Baseline:		155mA
CPU at 200MHz:		125mA
Unused LDOs off:	 85mA
Halt Glamo:		 70mA
CPU IDLE:		 45mA

With 45mA we're comfortably in a zone where we can run from USB.
GTA02v5 still isn't entirely happy, due to the high LED current,
but GTA02v6 should be okay. I'll make a patch later.

There's one remaining problem: why does my GTA02 shut down when
enabling the charger while there's no battery ?

I examined the PMU settings at various points (I've written a
pretty-printer for PMU and other register dumps,
http://svn.openmoko.org/developers/werner/greg/), and the only
thing that hints at a problem is that INT4.lowsys is set after
the sudden shutdown.

So it seems that the all-important Vsys wants closer examination,
to see if it's just unstable or if the source is indeed turned
off. That'll be fun ...

- Werner