[alsa-devel] ALSA : Can't open capture device

Alexandre BOUIN a.bouin at kerlink.fr
Fri Jan 11 11:56:02 CET 2008

Hi list, 

I'm working on an intern project, using an AT91SAM9260EK-based board,
embedded system.
Our kernel contains a full ALSA 1.14 with ASoC layer.
Our ASoC driver works well in capture and playback, if we are using OSS
layer or directly /dev/dsp.
So I need some tips on ALSA layer side :

here you can see that my device is created : 
ll /dev/snd/
crwxrwxrwx    1 root     root     116,   0 Dec 26  2007 controlC0
crwxrwxrwx    1 root     root     116,   4 Dec 26  2007 hwC0D0
crwxrwxrwx    1 root     root     116,  14 Dec 26  2007 pcmC0D0c
crwxrwxrwx    1 root     root     116,  16 Dec 26  2007 pcmC0D0p
ll /dev/dsp
crwxrwxrwx    1 root     root      14,   3 Dec 26  2007 /dev/dsp

A cat on playback device works (I added some traces in kernel) : 
cat < /dev/snd/pcmC0D0p
snd_pcm_open : enter
snd_pcm_open_file : before snd_pcm_open_substream
snd_pcm_open_file : after snd_pcm_open_substream
cat: read error: Invalid argument

But a cat on capture device does not work : 
cat < /dev/snd/pcmC0D0c
-sh: cannot open /dev/snd/pcmC0D0c: No such device

Any suggestion will be greatfull !!



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