[Community] GTA04 - Standby Time, Stable Kernel and Voice Quality

[NeilBrown]

On Tue, 22 Jan 2013 12:35:38 +0100 Jake Drexel <jackramone at googlemail.com>
wrote:

> Hi all,
> 
> As a current user of the gta02 I am concerned about the state of some
> shortcomings it had or still has in regard to the gta04.
> 
> Could someone share their experience in respect to:
>  * standby time (different scenarios, especially working as a phone only)

I think the current drain on the battery while the main CPU is suspended but
the 3G module is active, but in reasonably good coverage area, can definitely
get below 20mA, probably 15mA.  With GTA04A4 should be able to get a little
lower, maybe 10mA.

I have "off-mode" working in my current kernel (so most of the OMAP3 powers
off completely during suspend) which helped get from around 20mA down to around
15. Not completely certain of the results yet.  The A5 allows a couple more
components to be powered off completely which should save a couple of mA each.

A new battery claims 1200mAh, so that would be 120 hours or 5 days.  The
battery I'm using isn't that new, I only have the A3, and it has some strange
hardware issues (self inflicted) which I haven't figured out yet so I don't
get much more than 24hrs - I simply charge it every night.  I have "off-mode"
working in my current kernel (so most of the OMAP3 powers off completely
during suspend) which helped 

Obviously any time spent making calls or surfing the web will reduce that.  A
full battery might give you about 3 hours of solid web browsing.

>  * how stable is the kernel? esp. suspending (is that still used for
> power saving?)

Very stable.  Suspend and resume work quite reliably and quite quickly.  I
cannot promise it is 100% perfect as new releases come out and bugs do creep
in, but it really is quite solid.

Suspend is currently essential for power saving.  It should in theory be
possible to get a similar power saving without using suspend by letting
runtime PM and cpuidle reduce usage when nothing else is happening.  However
I think it would be a substantial challenge to achieve that in practice.  You
would need very well behaved user-space, and undoubtedly a number of fixes and
improvements to the kernel.  Might be an education project for someone though.


>  * audio quality while using as a phone

For the A3, which does software voice-routing, the call quality is adequate.
There is some echo, but I've heard worse on the occasional "commercial" phone
from big name vendors.
For the A4 and A5 the voice-routing is in "hardware" so the latency is lower
and thus there is less room for echo.  I haven't experienced it myself but I
suspect it is a good as most phones.

My biggest problem is that the 3G module is prone to crashing.  I have my own
software that talks to it and it is entirely possible that I'm doing some
silly things, but as the documentation is very thin it is hard to know what I
should be doing.  With the A3 I cannot power-cycle the modem from software so
I occasionally get into situations where I need to remove the battery.
For the A4 and A5 it is possible to force a power-cycle so you can definitely
programaticly restore functionality if it appears to be too sick.

The A5 is expected to have newer firmware which will have different bugs -
hopefully few of them


> 
> Thanks for your comments, any answers might bring me (and maybe
> others) closer to buy a gta04 ;-)

Good! Please buy :-)

NeilBrown

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