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  1. #1

    Post ALSA User program Help needed

    Hi All,

    I am writing a driver for one of the USB audio devices and i have been proceeding as per the document "Writing an ALSA driver", published in ALSA homepage.

    I am trying to create a user program but i am stuck as i am not able to open the device file.

    My call to open in my user application fails:

    snd_pcm_open fails with error "ALSA lib pcm.c:2212snd_pcm_open_noupdate) Unknown PCM /dev/snd/pcmC12D0p "
    where the last argument is my device file name(pcmCxDxp).

    I have tried passing the second argument as "hw:c,d" but the result is the same

    I have registered the device and the device files are also generated properly, but when i try to open the device file it fails.

    I am not sure where i am going wrong Can anybody throw some light on this.

    I have also checked the files generated according to number of USB interfaces and it seems to be fine.
    Also other commands like aplay -l etc seems to show my device properly

    Also "default" device opens fine.

    Last edited by pmr123; 08-16-2012 at 11:49 AM.

  2. #2
    Just Joined!
    Join Date
    Dec 2008
    Lund, Sweden
    I find it odd that the device would be called /dev/snd/pcmC12D0p, as normally the names are of the form CnDmp, where n is the card number, starting at 0 for the first card etc.

    When you've created the device file, have you given it the correct major/minor numbers? The fact that it says 'Unknown PCM' indicates that the device file exists but is not properly binding to the underlying driver.

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