[alsa-devel] [PATCH] ASoC: TWL4030: Fix 24bit support

Peter Ujfalusi peter.ujfalusi at nokia.com
Tue Dec 14 13:11:00 CET 2010

On Tuesday 14 December 2010 13:49:14 ext Mark Brown wrote:
> On Tue, Dec 14, 2010 at 01:45:29PM +0200, Peter Ujfalusi wrote:
> > twl4030 series of codecs supports S32_LE with msbits=24.
> > Replace the S24_LE with S32_LE format, and add constraint
> > for 24msbit in case of 32 S32_LE format.
> > 
> > Signed-off-by: Peter Ujfalusi <peter.ujfalusi at nokia.com>
> There's no real need to add the constraint for 24 bit - the CODEC will
> quite happily consume 32 bit data, it'll just ignore the 8 LSB.  We
> should probably do something more sensible with the format stuff, it's
> never been a terribly pressing issue though.

AFAIK this constraint is for applications to know, that only the 24 bit MSB is 
valid in S32_LE (for example the ice1712 also sets this constraint to let 
application know).
The datasheet of twl4030 series states, that it supports this coding, so IMHO it 
does not hurt to let applications know this fact.
But yeah, it will discard the the 8 bit LSB for sure.


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