[Gta04-owner] Donations to investigate suspend current?

Benjamin Deering ben_deering at swissmail.org
Thu Apr 10 14:23:50 CEST 2014


On 04/10/2014 03:06 AM, NeilBrown wrote:
> On Thu, 10 Apr 2014 08:26:34 +0200 Christoph Mair<christoph.mair at gmail.com>
> wrote:
>
>> Am 10.04.2014 01:49 schrieb "Benjamin Deering"<ben_deering at swissmail.org>:
>> Measuring less than 20mA with thermal imaging is quite hard, 
>> especially if you've got a multilayer board with lots of copper in it 
>> which spreads the heat... 
Thanks for the response, I wasn't sure of the limitations of thermal 
imaging.

> Would it make sense to collect donations specifically to fund some
thermal imaging to see what has changed?

Is there another specific goal that requires funding?  This is assuming 
that people are more likely to donate for a specific project than a 
general one.
>
> I could easily be wrong, but I think that a lot of the remaining power drain
> is related to the USB interface to the Option 3G chip.
> I'm certain that the drive for the EHCI interface on the OMAP3 has power
> management issues.  I suspect there might be interactions between it and the
> usb transceiver (parallel to serial converter) which waste power too.
I thought disabling usb during suspend saved a lot of power on 3.7 as 
well, but I may be remembering it wrong.
> Unfortunately the only way I can think of to make progress is to pour over
> the code in detail, read as much documentation for the EHCI interface as I
> can find, and try some things out.  i.e. lots and lots of work with no
> certainty of reward.
That sounds like it would be beyond my abilities, but I may take a look 
at what changed.

Ben


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