Power leakage: save 40mW by turning GSM on

Werner Almesberger werner at openmoko.org
Tue Feb 17 10:50:59 CET 2009

Rask Ingemann Lambertsen wrote:
>    Did you get any further with this?

Not yet. I've been a bit too busy with WLAN problems and travel
preparation the last weeks. But it's not forgotten ...

> 19 mA. However, contrary to what the wiki leads you to believe, you _do_
> turn off some sort of power to the modem by echoing 0 to
> /sys/bus/platform/devices/neo1973-pm-gsm.0/power_on.

You cut power to the GSM controller (another ARM), so there can be
a difference.

>    Given that power consumption was basicly the same 8,32 mW before and after
> the AT at POFF command, what exactly is that command supposed to do?

That's funny, though. It tells the PMU of the GSM subsystem to
shut down, similar to how we power off the main system (PMU state
"Standby", not to be confused with CPU suspend.)

- Werner

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