[alsa-devel] ASoC: Hooking a TI CODEC to a i.MX27 MCU

Stuart Longland redhatter at gentoo.org
Tue Jun 1 07:07:31 CEST 2010

On Tue, Jun 01, 2010 at 01:30:27PM +1000, Stuart Longland wrote:
> Hi Eric,
> On Fri, May 28, 2010 at 07:55:19AM +0200, Eric Bénard wrote:
> > Hi Stuart,
> Well, over the last few days I've been looking closely at the signals
> generated.  Especially this morning... yesterday, I managed to get some
> sound out of the CODEC when operating in I²S master mode (yes, I have a
> patch that I need to clean up first).
> What I observed is that despite being configured for I²S master, what I
> infact saw, was more like DSP mode, with a 1-bit frame sync pulse.  The
> remainder of my experimentation has been using the DSP modes of both MCU
> and CODEC.

Well, I managed to get the CODEC working as the I²S master, and managed
to get good quality audio.  The cause of my earlier DMA issues:  not
enabling DMA in the SSI device flags.  I guess I assumed this was the

Now I just have to get the audio level up to something that's reasonable
for the application ... the volume knob is somewhere amongst these
registers, now I just have to find it and turn it up (and make it
accessible via ALSA).  I'll look at cleaning up this driver and
submitting it for further work.
Stuart Longland (aka Redhatter, VK4MSL)      .'''.
Gentoo Linux/MIPS Cobalt and Docs Developer  '.'` :
. . . . . . . . . . . . . . . . . . . . . .   .'.'
http://dev.gentoo.org/~redhatter             :.'

I haven't lost my mind...
  ...it's backed up on a tape somewhere.

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