[alsa-devel] [PATCH] ASoC: sta32x: add workaround for ESD reset issue

Sven Neumann s.neumann at raumfeld.com
Thu Nov 10 17:49:19 CET 2011

On Thu, 2011-11-10 at 15:11 +0000, Mark Brown wrote:
> On Thu, Nov 10, 2011 at 03:27:08PM +0100, Johannes Stezenbach wrote:
> > On Wed, Nov 09, 2011 at 11:32:57PM +0000, Mark Brown wrote:
> > > Yeah, but if it suddenly stops in the middle of playback then that'll
> > > tend to register with users and if you keep it powered off at all other
> > > times.
> > Hm, the goal is to fix the issue without user interaction.
> > The app will keep the device open and will play back
> > without noticing the problem.
> Well, the user is going to hear a horrific glitch anyway...

Well, the problem we are facing here is not really showing up during
normal operation. The amplifier is resetting only if there's a strong
electrostatic discharge on the front panel of the device. This is most
likely only going to occur during an EMC test. To pass the EMC test a
short dropout is acceptable as long as the device continues normal
operation afterwards.

Of course there's a small likelihood that such an electrostatic
discharge will happen in real life, but we have never seen this
happening so far and if it will happen the user will most likely prefer
a short dropout over complete failure.


Sven Neumann
Head of RAUMFELD Software Development

Lautsprecher Teufel GmbH | Bülowstr. 66 | 10783 Berlin | Germany
Tel: +49 (0)30-300 930 153 | s.neumann at raumfeld.com

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