[Gta04-owner] 8mW sleep for Beagle Board

NeilBrown neilb at suse.de
Thu Jan 3 01:09:53 CET 2013


On Tue, 1 Jan 2013 16:29:45 +0100 Radek Polak <psonek2 at seznam.cz> wrote:

> Hi,
> i found this mail:
> 
> https://groups.google.com/forum/?fromgroups=#!topic/beagleboard/GXqO9rRsyCg
> 
> Do i count right? 8mW means 2mA on 4V battery. I wonder if we could apply this 
> also on GTA04.

The first patch is a useful guide for writing similar code for the GTA04.
The remainder aren't particularly relevant I think - the relevant
functionality is already in mainline.

I've recently refreshed my understanding of the power-use situation and how
to make some real progress on it soon.
There are two parts that are needed.
1/ the OMAP3 SoC need to enter 'off-mode' during suspend.
2/ the twl4030 needs to turn various regulators off during off-mode.

The patch patch in the post you linked addresses the 2nd point.

You can get SoC to enter off-mode by compiling with PM_DEBUG=y, and 
 echo 1 > /sys/kernel/debug/omap/enable-off-mode
(or some file name like that).

One problem is that when you resume from off mode the USB ports don't work.
This makes it hard to use the 3G modem for example.

So we need to find out why USB doesn't work, and fix that.
We also need to find out if off-mode breaks anything else.

NeilBrown
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