[alsa-devel] [PATCH] ASoC: OMAP: Fix DSP DAI format in McBSP DAI driver

[Jarkko Nikula]

On Wed, 22 Oct 2008 11:32:35 +0530
"ext Arun KS" <getarunks at gmail.com> wrote:

> Hi Jarkko,
> 
> I can get the audio playback working by applying this patch on
> tlvaic23 and osk5912. But capture is having a lot of noise.
> 
Thanks for testing!

Very interesting, the DSP modes in aic23 and aic33 are not compatible
and my patch was tuned according to aic33. In aic23 the falling edge of
FS starts the transfer in DSP mode where in aic33 it's opposite.

AIC23:
"
A falling edge on LRCIN or LRCOUT starts
the data transfer. The left-channel data consists of the first data
word, which is immediately followed by the right channel data word (see
Figure 3-8). Input word length is defined by the IWL register. Figure 3–
8 shows LRP = 1 (default LRP = 0).
"

AIC33:
"
In DSP mode, the rising edge of the word clock starts the data transfer
with the left channel data first and immediately followed by the right
channel data. Each data bit is valid on the falling edge of the bit
clock.
"

Wolfson's spec for WM9713 made it much more clear. The DSP_A there is
the same format what AIC23 is using and DSP_B is almost what AIC33 is
using but bit clock polarity is different.

http://www.wolfsonmicro.com/uploads/documents/en/WM9713.pdf

I'll fix omap-mcbsp.c so that DSP_A is the format what AIC23 and WM9713
are using and think later what to do with AIC33 and DSP_B :-)


Jarkko