[alsa-devel] [PATCH] ASoC: Tegra: Add support of tegra boards based on ALC5632 codec

[Stephen Warren]

Mark Brown wrote at Wednesday, November 23, 2011 3:46 PM:
> On Wed, Nov 23, 2011 at 02:30:12PM -0800, Stephen Warren wrote:
> > Mark Brown wrote at Wednesday, November 23, 2011 2:59 PM:
> 
> > > > That said, while these values are constant right now, I think they won't
> > > > always be; I think we'll need to switch between DSP mode for mono and
> > > > I2S mode for stereo here; at least I /think/ that's what I remember our
> > > > downstream drivers doing...
> 
> > > That would be a surprising restriction for your hardware to have.  From
> > > the CODEC point of view it really doesn't care at all, all the interface
> > > formats are interchangable.
> 
> > I believe Tegra20 HW "hard-codes" the channel count to 2 in I2S mode,
> > And hence always pulls 2 channels from the FIFO for each frame. So, I2S
> > can't do mono. This appears to be fixed in Tegra30. Tegra can be
> > surprising:-)
> 
> If it's got that restriction why not run it in PCM mode all the time?

That's a good idea. The internal feedback is that should work.

Leon, I'd suggest just hard-coding the current values into .dai_fmt as
Mark suggested. I'll take an action to investigate switching to DSP/PCM
mode, mono support, and switching the machine drivers (and I2S driver)
to it.

-- 
nvpublic