Setting up Alsa by hand on an embedded system

Setting up Alsa by hand on an embedded system

[David Smoot]

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OK, I tried this question about a month ago but I did not make it clear I
think.

I need to add the ability to record and playback audio on the embedded linux
platform my company uses.  Being embedded, I do not have a full Linux
distribution.  I have to set up ALSA by hand.  I can't simply untar the alsa
package and do ./configure followed by make.

Here's what I have done so far:
Rebuilt the kernel to have support for alsa and my chipset (an Intel ICH5
that uses the AC97 codec).
added the /dev/snd/ device nodes (I skipped the midi nodes because I do not
need them
copied libasound.so.2.0.0. from my host development box to the lib path on
my embedded box.  I added all the symlinks pointing to this library.

So I started by compiling some of the simple test programs, specifically the
ones from the LinuxJournal article on ALSA (
http://www.linuxjournal.com/article/6735).  The 4 sample programs run just
fine on my host system.  On my embedded system the command to open the PCM
device fails with:
ALSA lib pcm.c:2099:(snd_pcm_open_noupdate) Unknown PCM default
unable to open pcm device: No such file or directory

So I changed device name in the code from "default" to "plug:0,0" and it
still fails with the same message (but reads "plug:0,0" instead of default).

So what am I doing wrong?  Do I need a configuration file somewhere?  Do I
need to use a different argument for the PCM open?  Any suggestions?
David

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RE: Setting up Alsa by hand on an embedded system

[Steve DeRosier]

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Try an asound.conf file in /etc
 
To start, I'd try: 
---cutline---
default
{
  type hw
  card 0
  device 0 
}
---cutline---
 
But, you'll need it to match your specs.  Examine /proc/asound for your particular card and device params.  Also, refer to the asound.conf instructions on the website.  I'm not an asound.conf expert so ask again after experimenting, if you still can't get it to work.
 
- Steve

-----Original Message-----
From: David Smoot [mailto:davidsmoot@gmail.com]
Sent: Wednesday, December 21, 2005 5:36 PM
To: alsa-devel@lists.sourceforge.net
Subject: [Alsa-devel] Setting up Alsa by hand on an embedded system


OK, I tried this question about a month ago but I did not make it clear I think.

I need to add the ability to record and playback audio on the embedded linux platform my company uses.  Being embedded, I do not have a full Linux distribution.  I have to set up ALSA by hand.  I can't simply untar the alsa package and do ./configure followed by make. 

Here's what I have done so far:
Rebuilt the kernel to have support for alsa and my chipset (an Intel ICH5 that uses the AC97 codec).
added the /dev/snd/ device nodes (I skipped the midi nodes because I do not need them 
copied libasound.so.2.0.0. from my host development box to the lib path on my embedded box.  I added all the symlinks pointing to this library.

So I started by compiling some of the simple test programs, specifically the ones from the LinuxJournal article on ALSA ( http://www.linuxjournal.com/article/6735).  The 4 sample programs run just fine on my host system.  On my embedded system the command to open the PCM device fails with: 
ALSA lib pcm.c:2099:(snd_pcm_open_noupdate) Unknown PCM default
unable to open pcm device: No such file or directory

So I changed device name in the code from "default" to "plug:0,0" and it still fails with the same message (but reads "plug:0,0" instead of default). 

So what am I doing wrong?  Do I need a configuration file somewhere?  Do I need to use a different argument for the PCM open?  Any suggestions?
David




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Re: Setting up Alsa by hand on an embedded system

[Clemens Ladisch]

David Smoot wrote:
> I need to add the ability to record and playback audio on the embedded linux
> platform my company uses.  Being embedded, I do not have a full Linux
> distribution.  I have to set up ALSA by hand.  I can't simply untar the alsa
> package and do ./configure followed by make.

Have a look into alsa-lib's Makefile.am files to see what gets installed.

> ALSA lib pcm.c:2099:(snd_pcm_open_noupdate) Unknown PCM default

I guess the configuration files in /use/share/alsa/ are missing.


HTH
Clemens


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Re: Setting up Alsa by hand on an embedded system

[Asbjørn Sæbø]

On Wed, Dec 21, 2005 at 07:36:06PM -0600, David Smoot wrote:
> [...]
> So I started by compiling some of the simple test programs, specifically the
> ones from the LinuxJournal article on ALSA (
> http://www.linuxjournal.com/article/6735).  

You noticed the comment about the bug in some of the listings?  The 
variable "dir" must be initialized to zero, or segfaults may occur.

Asbj.S.


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Re: Setting up Alsa by hand on an embedded system

[David Smoot]

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I don't the dir variable is the issue because I am not getting segfaults.
The code compiles and works on my "host machine" (full debian box) but does
not on my embedded.

It appears that combining the two suggestions from Clements and Steve have
gotten me further.  It appears that the file /usr/share/alsa.conf loads the
default configuration and also loads the file in /etc/asound.conf.  I get a
different error now, I think I need to tweak the files in /usr/share/alsa to
match the correct chipset.

Does the alsa configuration environment require python?  My embedded system
does not have python.  I'm sure I will have to hack it in someday but it is
not there yet.

I've gotten further but a few more errors but I think you all have gotten me
on the correct track.  Thank you.

David

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Re: Setting up Alsa by hand on an embedded system

[Steve deRosier]

Hm, yeah, I missed the /usr/share/alsa stuff.  Whoops.

We don't have python on our box, so I'd guess you'd be fine.

- Steve

David Smoot wrote:
> I don't the dir variable is the issue because I am not getting 
> segfaults.  The code compiles and works on my "host machine" (full 
> debian box) but does not on my embedded.
> 
> It appears that combining the two suggestions from Clements and Steve 
> have gotten me further.  It appears that the file /usr/share/alsa.conf 
> loads the default configuration and also loads the file in 
> /etc/asound.conf.  I get a different error now, I think I need to tweak 
> the files in /usr/share/alsa to match the correct chipset.
> 
> Does the alsa configuration environment require python?  My embedded 
> system does not have python.  I'm sure I will have to hack it in someday 
> but it is not there yet.
> 
> I've gotten further but a few more errors but I think you all have 
> gotten me on the correct track.  Thank you.
> 
> David


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