[Community] GTA04A5 / Letux 2804 - Power Management

Dr. H. Nikolaus Schaller hns at goldelico.com
Thu Jan 16 12:00:28 CET 2014


Am 16.01.2014 um 11:42 schrieb Christ van Willegen:

> On Thu, Jan 16, 2014 at 11:21 AM, Dr. H. Nikolaus Schaller
> <hns at goldelico.com> wrote:
>> Yes, I agree that it has to be fixed. Volunteers?
>> Ok, please help to fix the power management (in the latest kernel because
>> everything else makes no sense to me and is unlikely to get outside
>> support).
> I have something in mind that _may_ point to a possible source of the
> 'missing mA's'...
> I assume that most hardware is put into low/high power mode
> (active/inactive) using GPIO settings. Is that correct?
> My idea was to create a log file (somewhere in /tmp) from the kernel
> code that does the GPIO switching. This file would look like:
> [/sys/power/state] [GPIO number] [GPIO state]
> :
> That way, we could inspect if the GPIOs are in the correct state for
> the correct power state. And, if not, try to figure out where the
> GPIOs should (have) be(en) set to get the correct results.

Yes, that is a really interesting idea.

> Any other culprits may, perhaps, be found in a similar way (I2C
> commands logged?)
> Not sure if this would track _every_ mA, but perhaps it can point in
> the right direction...
> Also not sure if I can handle this, I did look into the (3.7) kernel
> sources breifly, but building a kernel takes so mnuch time on GTA04
> that it's not practical to do dev. work on it. Also, I don't have a
> 3.12 (or 3.13...) kernel source on it, but that could probably be
> fixed.

Kenrel sources are here:


The master branch is based on 3.12.7


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