[alsa-devel] [PATCH 2/3] ASoC: omap-mcbsp: change the DSP_B mode to DSP_A mode

[Jarkko Nikula]

On Thu, 9 Apr 2009 12:16:55 +0200
"Ujfalusi Peter (Nokia-D/Tampere)" <peter.ujfalusi at nokia.com> wrote:

> > Are you absolutely sure on this? According to WM9713, it's the DSP_A
> > where MSB is valid after 1 bit clock period of the FS.
> 
> I think this is correct. The data is going to be valid exactly the
> same way, as the WM9713 data sheet describes.
> 
I'll try to find working commit where my Beagle is still booting since
it wasn't with the head of linux-omap and then playing a bit with
McBSP3 which is available in pin header of the Beagle so we can measure
this out easily.

> As for the DSP_B mode: I think it can be implemented like this:
> Invert the frame sync polarity, Then:
> 	case SND_SOC_DAIFMT_DSP_B:
> 		regs->srgr2	|= FPER(wlen * channels - 1);
> 		regs->srgr1	|= FWID(0); /* FS pulse width is 1

Looks nice idea. BTW, I had temporary inversion in use in the commit
da6320becf31c40b60d4b1dc6b339c9a766b671c.


Jarkko