[Gta04-owner] Power consumption with 3.12

[Dr. H. Nikolaus Schaller]

Am 07.11.2013 um 13:41 schrieb Benjamin Deering:

> Hello all,
> 
> My gta04 is working pretty well right now, even if there are several hacks required.
> 
> I can listen to the radio, take pictures, use gps, send and receive phonecalls.

++

> 
> Right now the biggest problem is power consumption.
> 
> For a while, the phone would use ~600ma at boot (this was the wifi power problem) until I scanned for wifi access points and turned it off again.  After this I would see idle power ~195ma and suspend ~80ma.
> 
> Starting with the first kernel to fix this bug, I saw idle power closer to 300ma and suspend still around 80ma.
> 
> I just tried disabling omap3_isp and am again seeing ~200ma at idle but I doubt that is related to the wifi change.  With omap3_isp disabled I did see 53-56ma suspend.

Ok, maybe the ISP driver does not support suspend?

> 
> https://linuxtv.org/patch/7836/  I don't fully understand this, but it sounds like they disable some cpuidle features when camera is active, but maybe our camera driver says it is always active?  Maybe I will try to look at this tonight.

From the dmesg printk() that are still in the driver I think the camera is only powered up and each time you open the video device. So we either have a bug there (i.e. it is not really powered down although it tells) or the ISP subsystem does not suspend (clocks disabled?).

> 
> Another change I noticed in newer kernels is that iio drivers don't seem to allow for powering things off (polling rate can't be set to 0, etc).  I will try making hmc a module and disabling it to see if there is an effect.

Interesting observation. Well, the HMC + other iio devices can well draw some mA but not ~30.
Maybe we should start without any peripheral driver (as modules - except the absolutely necessary ones).

Unfortunately I can't spend more time to spend on this topic although it is tempting to take this challenge... Maybe after Neo900 and GTA04A5.

BR,
Nikolaus