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

[Stuart Longland]

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
default.

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.