How to Change the Primary USB Audio Device

Follow these steps if you remove or change your USB audio devices and you want to make one particular audio device the primary audio device. The procedure changes the primary audio device to the onboard audio device as an example.

1. Become superuser.

2. Close all audio applications.

3. Verify that the audio and USB drivers are loaded.

   # modinfo | grep -i audio 124 780e6a69 bb6e - 1 audiosup (Audio Device Support 1.12) # modinfo | grep -i usb 48 13dba67 18636 199 1 ohci (USB OpenHCI Driver 1.31) 49 78020000 1dece - 1 usba (USBA: USB Architecture 1.37) 50 12e5f1f 35f 195 1 hubd (USB Hub Driver 1.4) 51 13ef53d 5e26 194 1 hid (USB HID Client Driver 1.16) 54 13f67f2 1b42 10 1 usbms (USB mouse streams 1.6) 56 127bbf0 2c74 11 1 usbkbm (USB keyboard streams 1.17) #

   
   

4. Load and attach the onboard audio driver.

   # devfsadm -i audiocs

   
   

   The onboard audio driver is audiocs on a Sunblade 1000, and audiots on a Sunblade 100.

5. Verify that the primary audio device link is pointing to the onboard audio.

   # ls -lt /dev/audio* lrwxrwxrwx 1 root other 7 Jul 23 15:49 /dev/audio -> sound/0 lrwxrwxrwx 1 root other 10 Jul 23 15:49 /dev/audioctl -> sound/0ctl # ls -lt /dev/sound/* lrwxrwxrwx 1 root other 66 Jul 23 14:21 /dev/sound/0 -> ../../devices/pci@1f,4000/ebus@1/SUNW,CS4231@14,200000:sound,audio lrwxrwxrwx 1 root other 69 Jul 23 14:21 /dev/sound/0ctl -> ../../devices/pci@1f,4000/ebus@1/SUNW,CS4231@14,200000:sound,audioctl #

   
   

6. Confirm the onboard audio is the primary audio device.

   % audioplay /usr/demo/SOUND/sounds/bark.au

   
   

   The audioplay command defaults to the onboard audio device.

7. (Optional) Unload all the audio drivers that can be unloaded before plugging in another USB audio device.

   1. Close all the audio applications.

   2. Display the audio driver information to verify that no audio drivers are currently loaded.

      # modinfo | grep -i audio 60 78048000 bb6e - 1 audiosup (Audio Device Support 1.12) 61 78152000 39a97 - 1 mixer (Audio Mixer 1.49) 62 78118000 bf9f - 1 amsrc1 (Audio Sample Rate Conv. #1 1.3) 128 7805e000 14968 54 1 audiocs (CS4231 mixer audio driver 1.21) #

      
      

   3. Unload the audio drivers.

      # modunload -i 0 # modinfo | grep -i audio 60 78048000 bb6e - 1 audiosup (Audio Device Support 1.12) 61 78152000 39a97 - 1 mixer (Audio Mixer 1.49) #

      
      

      At this point, audiocs, the onboard audio driver, has been unloaded and guaranteed not to be open. However, the primary audio device, /dev/audio, does not change if it is held open by an application.

8. (Optional) Plug in a USB audio device.

9. (Optional) Examine the new audio links.

   % ls -lt /dev/audio* lrwxrwxrwx 1 root root 7 Jul 23 16:12 /dev/audio -> sound/1 lrwxrwxrwx 1 root root 10 Jul 23 16:12 /dev/audioctl -> sound/1ctl % ls -lt /dev/sound/* lrwxrwxrwx 1 root root 77 Jul 23 16:12 /dev/sound/1ctl -> ../../devices/pci@1f,4000/usb@5/hub@1/device@3/sound-control@0:sound,... lrwxrwxrwx 1 root root 74 Jul 23 16:12 /dev/sound/1 -> ../../devices/pci@1f,4000/usb@5/hub@1/device@3/sound-control@0:sound,... lrwxrwxrwx 1 root root 66 Jul 23 15:59 /dev/sound/0 -> ../../devices/pci@1f,4000/ebus@1/SUNW,CS4231@14,200000:sound,audio lrwxrwxrwx 1 root root 69 Jul 23 15:59 /dev/sound/0ctl -> ../../devices/pci@1f,4000/ebus@1/SUNW,CS4231@14,200000:sound,aud... %

   
   

Troubleshooting USB Audio Device Problems

This section describes how to troubleshoot USB audio device problems.

Solving USB Audio Problems

Sometimes USB speakers do not produce any sound even though the driver is attached and the volume is set to high. Hot-plugging the device might not change this behavior.

The workaround is to power cycle the USB speakers.

Key Points of Audio Device Ownership

Keep the following key points of audio device ownership in mind when working with audio devices.

• When you plug in a USB audio device and you are logged in on the console, the console is the owner of the /dev/* entries. This situation means you can use the audio device as long as you are logged into the console.

• If you are not logged into the console when you plug in a USB audio device, root becomes the owner of the device. However, if you log into the console and attempt to access the USB audio device, device ownership changes to the console. For more information, see logindevperm(4).

• When you remotely login with the rlogin command and attempt to access the USB audio device, the ownership does not change. This means that, for example, unauthorized users cannot listen to conversations over a microphone owned by someone else.

Hot-Plugging USB Devices With the cfgadm Command (Task Map)