[LAU] Error enabling dmix with ALSA

Patrick Shirkey pshirkey at boosthardware.com
Sat Aug 15 10:01:23 EDT 2009


On 08/15/2009 11:06 PM, ruchi sirauthiya wrote:
> Hi,
>
> I am trying to enable a software mixer (using ALSA and dmix) on an 
> OMAP3 based embedded target board using the twl4030 codec.
>
> When I try to play audio using the command,
>
> # aplay -D playback rec.wav
>
> I am getting the following error:
>
> ALSA lib pcm_direct.c:1098:(snd_pcm_direct_initialize_poll_fd) unable to
> open timer 'hw:CLASS=3,SCLASS=0,CARD=0,DEV=0,SUBDEV=0'
> ALSA lib pcm_dmix.c:943:(snd_pcm_dmix_open) unable to initialize poll_fd
> aplay: main:546: audio open error: No such file or directory
>

According to this thread the drivers can't open a second timer on your 
device.

http://osdir.com/ml/linux.distributions.crux.general/2005-11/msg00134.html


Probably best to contact alsa-dev directly on this one.


Warmest regards.

Patrick Shirkey
Boost Hardware Ltd






> The contents of my /etc/asound.conf is given below.
>
> pcm.playback {
>    type dmix
>    ipc_key 2048
>    ipc_key_add_uid true
>    ipc_gid 1
>    slave {
>       rate 44100
>       pcm hw:0
>    }
> }
>
> I have tested it on two kernel versions, 2.6.22 and 2.6.29, but it 
> fails on both.
> Playback and recording works fine if -D option is not provided.
>
> I also tried configuring ALSA (dmix) with a different configuration 
> file which is given in the following link:
> http://amarok.kde.org/wiki/Setting_up_Dmix_for_ALSA
>
> # aplay -D plug:ossmix /mnt/Audio1_1.wav
> ALSA lib pcm_direct.c:1098:(snd_pcm_direct_initialize_poll_fd) unable 
> to open timer 'hw:CLASS=3,SCLASS=0,CARD=0,DEV=0,SUBDEV=0'
> ALSA lib pcm_dmix.c:943:(snd_pcm_dmix_open) unable to initialize poll_fd
> aplay: main:546: audio open error: No such file or directory
>
> But as you can see the same error turns up again.
>
> What could be the cause of this error?
>
> Is the above error related to ALSA configuration (for dmix)?
> Do I need to patch the kernel or ALSA for using dmix?
>
> Please help me resolve this issue. Let me know if any more setup info 
> is required.
>
> Thanks and Regards,
>
> Ruchi Sirauthiya.
>
>
>
> Some information I obtained from the proc filesystem is given below 
> for your reference.
>
> -----------------------
> For Linux kernel 2.6.29
> -----------------------
>
> [root at OMAP3 tests]# cat /proc/asound/version
> Advanced Linux Sound Architecture Driver Version 1.0.19
> [root at OMAP3 tests]# cat /proc/asound/cards
>  0 [omap3evm       ]: twl4030 - omap3evm
>                       omap3evm (twl4030)
>
> [root at OMAP3 tests]# omap-dss: Could not find exact pixel clock. 
> Requested 25188 kHz, got 25187 kHz
>
> [root at OMAP3 tests]# cat /proc/asound/devices
>   2:        : timer
>   3: [ 0- 0]: digital audio playback
>   4: [ 0- 0]: digital audio capture
>   5: [ 0]   : control
>
> [root at OMAP3 tests]# cat /proc/asound/timers
> G0: system timer : 7812.500us (10000000 ticks)
> P0-0-0: PCM playback 0-0-0 : SLAVE
> P0-0-1: PCM capture 0-0-1 : SLAVE
>
> [root at OMAP3 tests]# cat /proc/asound/pcm
> 00-00: TWL4030 twl4030-0 :  : playback 1 : capture 1
>
> [root at OMAP3 tests]# cat /proc/asound/devices
>   2:        : timer
>   3: [ 0- 0]: digital audio playback
>   4: [ 0- 0]: digital audio capture
>   5: [ 0]   : control
>
> [root at OMAP3 tests]# cat /proc/asound/pcm
> 00-00: TWL4030 twl4030-0 :  : playback 1 : capture 1
>
> [root at OMAP3 tests]# cat /proc/asound/oss/devices
>   3: [0- 0]: digital audio
>   4: [0- 0]: digital audio
>
> [root at OMAP3 tests]# cat /proc/asound/oss/sndstat
> Sound Driver:3.8.1a-980706 (ALSA v1.0.19 emulation code)
> Kernel: Linux OMAP3 2.6.29-rc3-omap1 #1 Fri Jul 24 14:45:37 IST 2009 
> armv7l
> Config options: 0
> Installed drivers:
> Type 10: ALSA emulation
>
> Card config:
> omap3evm (twl4030)
>
> Audio devices:
> 0:  (DUPLEX)
>
> Synth devices: NOT ENABLED IN CONFIG
>
> Midi devices: NOT ENABLED IN CONFIG
>
> Timers:
> 31: system timer
>
> Mixers: NOT ENABLED IN CONFIG
>
> [root at OMAP3 tests]# aplay -D playback /mnt/Audio1_1.wav
> ALSA lib pcm_direct.c:1098:(snd_pcm_direct_initialize_poll_fd) unable 
> to open timer 'hw:CLASS=3,SCLASS=0,CARD=0,DEV=0,SUBDEV=0'
> ALSA lib pcm_dmix.c:943:(snd_pcm_dmix_open) unable to initialize poll_fd
> aplay: main:546: audio open error: No such file or directory
>
>
> -----------------------
> For Linux kernel 2.6.22
> -----------------------
>
> [root at OMAP3 tests]# cat /proc/asound/devices
>   2:        : timer
>   3: [ 0- 0]: digital audio playback
>   4: [ 0- 0]: digital audio capture
>   5: [ 0]   : control
>
> [root at OMAP3 tests]# cat /proc/asound/pcm
> 00-00: OMAP PCM : omap alsa pcm : playback 1 : capture 1
>
> [root at OMAP3 tests]# cat /proc/asound/timers
> G0: system timer : 7812.500us (10000000 ticks)
> P0-0-0: PCM playback 0-0-0 : SLAVE
> P0-0-1: PCM capture 0-0-1 : SLAVE
>
> [root at OMAP3 tests]# cat /proc/asound/
> /proc/asound/TWL4030/  /proc/asound/devices   /proc/asound/timers
> /proc/asound/card0/    /proc/asound/hwdep     /proc/asound/version
> /proc/asound/cards     /proc/asound/pcm
>
> [root at OMAP3 tests]# cat /proc/asound/cards
>  0 [TWL4030        ]: OMAP_ALSA - TWL4030
>                       TWL4030
> /proc/asound/oss was not found in the proc file system when booted 
> with kernel 2.6.22.
> ------------------------------------------------------------------------
>
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