[Gta04-owner] Another few milliamps.

Fred . frederi1 at gmail.com
Sun Mar 18 23:04:24 CET 2012


Hi

On Sun, Mar 18, 2012 at 10:56 PM, NeilBrown <neilb at suse.de> wrote:

>
> I recently turned the volume on my gta04 way up so that the alarm sound
> would
> be clearly audible from the other room.
> I was subsequently surprised to notice that there was a faint white-noise
> hum
> coming from it while it was suspended.
>
> It seems that the audio codec is not being turned off - either when not in
> use, or in suspend.
>
> I confirmed this with printks in twl4030_codec_enable() in
> sound/soc/codecs/twl4030.c.
>
> I hacked that function to always disable - never enable - and measured the
> suspend current.  It had dropped from about 46mA to about 42mA.
>
> So it seems we are wasting a few milliamps by leaving the codec on.
>
> The code looks correct: twl4030_soc_suspend() calls
> twl4030_set_bias_level(SND_SOC_BIAS_OFF), and that calls
> twl4030_codec_enable(0), which will power off the codec.
>
> But some how some part of that isn't happening.
>
> I won't have time to look more deeply into this for a while, but if someone
> has time and wants to hunt around in the code - insert lots of printks

 Is it possible to debug with a copy of the RAM saved by some u-boot
command?
I suppose the kernel is at least logging to RAM its last actions before
shuting off...

> and
> figure out why the codec isn't being turned off, I'm sure it would be a lot
> of fun.
>
> (this is in 3.2-gta04)
>
> NeilBrown
>
> _______________________________________________
> Gta04-owner mailing list
> Gta04-owner at goldelico.com
> http://lists.goldelico.com/mailman/listinfo/gta04-owner
>
>


-- 
http://www.avaaz.org
http://www.avaaz.org/fr/index.php
http://www.avaaz.org/stat/new/images/blue/logo_fr.png/1331309272
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.goldelico.com/pipermail/gta04-owner/attachments/20120318/870d0d89/attachment.html>


More information about the Gta04-owner mailing list