[Gta04-owner] Another few milliamps.

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


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
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
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> Gta04-owner at goldelico.com
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