[alsa-devel] [PATCH] ASoC: tlv320aic3x: Fix mono

[Benoît Thébaudeau]

On Saturday, January 26, 2013 9:55:14 AM, Mark Brown wrote:
> On Fri, Jan 25, 2013 at 06:19:20PM +0100, Benoît Thébaudeau wrote:
> > The TLV320AIC3x DAI supports only stereo. This patch fixes mono support for
> > this
> > codec by allowing only stereo at codec level.
> 
> So, this doesn't actually fix mono - it removes support for it.

Yes, for this driver, but this fixes mono for the whole system, meaning that
e.g. it fixes mono playback support with players like MPlayer. I will reword if
you prefer.

>  It's a
> bit surprising that this is a requirement actually, the device seems to
> support DSP modes which usually do mono totally happily (I2S style modes
> have problems due to the clocking).  I'd like to see some confirmation
> that there's not some other issue in your system...

I've only tested with I²S (imx-ssi). But for all the available DAI modes, the
data sheet gives the encoding for both stereo channels (from p. 21), and nowhere
it says that mono is an option for DAI:
http://www.ti.com/lit/ds/symlink/tlv320aic3104.pdf

I will retest with DSP modes if you prefer.

The idea was the same as for this commit:
http://git.kernel.org/?p=linux/kernel/git/next/linux-next.git;a=commitdiff;h=37f45cc54cb03cac4a6b865b32bc705bb0cb1d29
Even though the MC13783 only supports I²S and MSB justified modes, and there may
be an issue specific to it:
http://cache.freescale.com/files/rf_if/doc/data_sheet/MC13783.pdf?pspll=1

Best regards,
Benoît