[pulseaudio-discuss] Two identical USB sound-cards - second card fails to load because card-name found in hashmap.

[Chris Gilland]

Is it possible that sense you have two of the exact same cards, maybe one of them isn't working as there is an I R Q conflict between both of them?  I'll admit my expertees on Pulse Audio are not very good at all, and probably I shouldn't be making this assumption being I really don't totally know what I'm doing, admittedly, but it is a thought.

Chris.

  ----- Original Message ----- 
  From: Ivar Mossin 
  To: pulseaudio-discuss at mail.0pointer.de 
  Sent: Saturday, August 21, 2010 3:51 PM
  Subject: [pulseaudio-discuss] Two identical USB sound-cards - second card fails to load because card-name found in hashmap.


  Hello.

  I'm having problems loading two identical sound-cards in my computer. I'm using Ubuntu 9.10 and PulseAudio 0.9.19 coming with this release.

  I have tried looking at the logs, and when using loglevel 4 I find these lines:

  (first card - failing scenario):
  Aug  9 22:53:08 ivar-laptop pulseaudio[2573]: module.c: Loaded "module-alsa-card" (index: #24; argument: "device_id="1" name="usb-BeAutiful_Qing_Audioengine_AW1-00" card_name="alsa_card.usb-BeAutiful_Qing_Audioengine_AW1-00" tsched=yes ignore_dB=no card_properties="module-udev-detect.discovered=1"").

  (second card - failing scenario):
  Aug  9 22:58:32 ivar-laptop pulseaudio[2573]: module.c: Failed to load  module "module-alsa-card" (argument: "device_id="2" name="usb-BeAutiful_Qing_Audioengine_AW1-00" card_name="alsa_card.usb-BeAutiful_Qing_Audioengine_AW1-00" tsched=yes ignore_dB=no card_properties="module-udev-detect.discovered=1""): initialization failed.


  I downloaded the source-code using 'apt-get source pulseaudio' and was looking around a bit. What I found was that the pa__init() function in modules/alsa/module-alsa-card.c called a function pa_card_new() located in pulsecore/card.c which returned a null-pointer. This function again called pa_namereg_register() in pulsecore/namereg.c which returned NULL because it could find the card-name in the hashmap and the fail argument was set to TRUE. As a simple test, I changed the fail argument to FALSE, and the second module loaded as well:

  (first card - working scenario):
  Aug 21 18:10:03 ivar-laptop pulseaudio[3835]: module.c: Loaded "module-alsa-card" (index: #18; argument: "device_id="2" name="usb-BeAutiful_Qing_Audioengine_AW1-00" card_name="alsa_card.usb-BeAutiful_Qing_Audioengine_AW1-00" tsched=yes ignore_dB=no card_properties="module-udev-detect.discovered=1"").

  (second card - working scenario):
  Aug 21 18:12:37 ivar-laptop pulseaudio[3835]: module.c: Loaded "module-alsa-card" (index: #19; argument: "device_id="3" name="usb-BeAutiful_Qing_Audioengine_AW1-00" card_name="alsa_card.usb-BeAutiful_Qing_Audioengine_AW1-00" tsched=yes ignore_dB=no card_properties="module-udev-detect.discovered=1"").


  Having this flag set to TRUE basically disables the functionality further down in the pa_namereg_register() which tries to add a ".%u" to the card-name, where %u starts at 2 and gives up at 99. Trying to figure out where this flag was set, I found that it had been set by a function set_card_name() called further up in pa__init(). If the module being loaded has the argument "card_name" or "name", then data->namereg_fail is set to TRUE. Looking at the arguments given in the logfile, it actually provides both of these arguments, also at load-time:

  (second card - failing scenario):
  Aug  9 22:58:32 ivar-laptop pulseaudio[2573]: module-udev-detect.c: Loading module-alsa-card with arguments 'device_id="2" name="usb-BeAutiful_Qing_Audioengine_AW1-00" card_name="alsa_card.usb-BeAutiful_Qing_Audioengine_AW1-00" tsched=yes ignore_dB=no card_properties="module-udev-detect.discovered=1"'


  So my questions are:
  Is there a way to load both these cards without modifying the source?
  Can I configure something to make this work?
  What is the reasoning behind setting this flag at all?
  Which side-effect will I experience by simply ignoring this flag, and trying to add a ".%u" to the card-name anyway?

  Thanks for any help provided.


  Kind Regards,
  Ivar Mossin



------------------------------------------------------------------------------


  _______________________________________________
  pulseaudio-discuss mailing list
  pulseaudio-discuss at mail.0pointer.de
  https://tango.0pointer.de/mailman/listinfo/pulseaudio-discuss
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.freedesktop.org/archives/pulseaudio-discuss/attachments/20100821/ae65c783/attachment.htm>