[Gta04-owner] 4.3-rc6 available

H. Nikolaus Schaller hns at goldelico.com
Mon Oct 19 08:39:59 CEST 2015


Hi all,
I have upgraded to 4.3-rc6 and
* integrated omapdrm drivers (and xorg.conf)
* integrated Neil's power measure-suspend script

Here is the uImage + link to sources:

	http://download.goldelico.com/gta04-kernel/4.3-rc6/

USB charging is still broken. Anyone with an idea or fix?

And, I have done some simple suspend tests
and came to an interesting conclusion:

root at letux:~# ./measure-suspend 10
suspending for 10 seconds
did wake up
192960 uA over 10 seconds
root at letux:~# ./measure-suspend 20
suspending for 20 seconds
did wake up
128520 uA over 20 seconds
root at letux:~# ./measure-suspend 30
suspending for 30 seconds
did wake up
107040 uA over 30 seconds
root at letux:~# ./measure-suspend 40
suspending for 40 seconds
did wake up
80280 uA over 40 seconds
root at letux:~#


It is really unexpected that the average is going down such
significantly.

This indicates that the system is drawing a lot of energy,
for some initial seconds and then goes down.

Let's try to model it by

Iavg = (Iinitial * initial + Isuspend * (total - initial)) / total

where initial is the initial time with high current and total the
total time.

There are 3 unknown variable (Iinitial, Isuspend, initial)

So we have to solve 3 equations, e.g.

192 * 10 = Iinitial * initial + Isuspend * (10 - initial)
128 * 20 = Iinitial * initial + Isuspend * (20 - initial)
80 * 40 = Iinitial * initial + Isuspend * (40 - initial)

An approximate solution is (haven't tried to exactly solve the equation system):

Iinitial = 4 s
Isuspend = 50 mA
initial = 400 mA

So this means that it takes 4 seconds after suspend
until power is really going down. So a suspend with
less than 4 seconds has no effect. Interesting.

BR,
Nikolaus



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