[alsa-devel] [PATCH 4/4] ASoC: TWL4030: Add pre-DAC digital mux controls

Peter Ujfalusi peter.ujfalusi at nokia.com
Mon Dec 1 13:09:40 CET 2008

Hello Mark,

On Monday 01 December 2008 13:43:48 ext Mark Brown wrote:
> On Mon, Dec 01, 2008 at 10:03:48AM +0200, Peter Ujfalusi wrote:
> > Controls for selecting the digital inputs for the four
> > DAC.
> How often is this feature used at the minute?  While I've got no problem
> with the code per se there's currently no framework in ASoC for handling
> digital routing which means that having the flexibility creates problems
> with DAPM (which isn't implemented yet for this codec).  There's no real
> issue merging it, but it might make life easier to leave it for now.

Well, I'm not sure how often this can be used. I was reading the wm* codec
drivers as you suggested a while ago. Those also implement the digital routing
outside of DAPM. So I thought why not.
Most of the times these routings are static, so one can set these from the actual
board file, it is kind of hackish, but could do it:
codec->write(codec, TWL4030_REG_RX_PATH_SEL, _something_);
I don't see to much harm on having it as runtime configurable. As I said I think
it is good to have 'full control' over things.

About the DAPM things:
Now I'm in the process of adding the DAPM mappings for TWL (the Earpiece out now works with DAPM).
Altrough there are some obstacles on the road, but slowly and steadily I'm getting there.

One more thing: I have asked around the availability of technical documentation for TWL.
My copy has the big sign: Sigend NDA is required for Distribution...
But, the TPS65950 (also from TI) has the very same audio block as the TWL and the TRM is
publically available here:

> Implementing digial routing support is on my radar but it's firmly below
> the V2 merge.

You obviously know about ASoCv2... Do you have some pointers on what is coming and when?


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