[Community] GTA04 - Power management improvements

Hermann Schwärzler hermann.schwaerzler at chello.at
Wed Jan 29 09:07:28 CET 2014


Hello

On 01/28/2014 11:27 AM, Dr. H. Nikolaus Schaller wrote:
> 
> Am 28.01.2014 um 10:28 schrieb Hermann Schwärzler:
[...]
>> No I did not use such a script. Just the "poweroff" command of the
>> system. Tonight I will power off after running this script and will
>> report my findings.
> 
> Ok.

I can confirm that powering down the modem before powering down the
device results in ~0 power usage!

I used the modem-poweroff.sh script in /opt/qtmoko/bin/ yesterday
evening before calling "poweroff" on the device and after powering it on
this morning (after 9:25 hours) I saw a mere 5mAh decrease in the
charge-value of the battery. I saw this *after* boot so most/all of it
is due to power-usage of the boot process.

As far as I can tell the modem-poweroff.sh script is not used anywhere
in qtmoko. So I propose to call it when a device-shutdown is requested.
E.g. in QtopiaServerApplication::shutdown()? But this is for sure
device-dependent so there might be a better place...


>> But there remains the power-usage of a suspended device (that has no
>> need to communicate with the base station as it lies on the same place
>> all the time and receives neither calls nor text-messages): If
>> communcation with the base station draws 100 mA the device would have to
>> communicate 19% of the time with the station to get an average current
>> of 20.9 mA...
> 
> Well, in suspend the CPU is in sleep mode and the DRAM in self-refresh. This
> still needs some mA.
> 
> And we know that the IrDA receiver may still be turned on (known bug in GTA04A4
> hardware). Since I don't know exactly what the Neil-kernel
> does in suspend it may even be the RS232 that is not turned off.

Is there anything I can do to check this?
Is there a way to turn off IrDA and/or RS232 explicitely (similar to the
modem)?

Greetings
Hermannn



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