[alsa-devel] Exporting playback and capture capability to user space

Vinod Koul vinod.koul at linux.intel.com
Mon Nov 21 07:23:46 CET 2011

On Mon, 2011-11-21 at 11:19 +0530, Rajeev kumar wrote:
> Hello Mark
> Could you please help me by answering these questions?
> Best Regards
> Rajeev
Pls don't top-post!!
> On 11/17/2011 7:05 PM, Rajeev kumar wrote:
> > Hello Mark
> >
> > I have a single codec with playback and capture capability. We are using
> > it for different i2s controller. Below are the details for that.
> >
> > case 1: I2S controller-1: with playback and capture capability
> > case 2: I2S controller-2: with playback capability only
> > case 3: I2S controller-3: with capture capability only.
> >
> > We are registering all the I2S controller with there respective capability.
> >
> > In command 'aplay -l' or 'cat /proc/asound/pcm', among playback devices,
> > capture device is also listed. This is true in case-1 but for case-2 and
> > case-3 also it is showing the same behavior. According to my
> > understanding it should not show the list of all devices i.e. in case of
> > controller having playback capability it should show only playback
> > devices not capture devices and vice versa. Please correct me if I am
> > wrong.
> >
> > So my questions are
> > 1. How to separate playback and capture devices in case-2 and case-3.
> > Are we need to register different codec for different i2s controller?
How asoc builds this is based on dailinks you have provided. If for the
device 2 and device 3 the cpu and codec dais support both playback and
capture devices, it will go ahead and register these device.
The fact that for device 2 and device 3 capture is also registered
suggests me that your cpu dais are not correct.

Would help if you post your code, esp the codec, cpu dais and dialinks.


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