uaudio problem with USB Sound Blaster mp3+

[Winfried Maus]

On 5.3-RELEASE, a system freeze occurs when an application tries to
use the USB audio device.

On 5.4-BETA1, there is no system freeze, but uaudio does not create
/dev/dsp and no sound device is available.

Here are some extracts from dmesg:

[...]
ugen0: Creative USB Audio, rev 1.10/1.00, addr 5
ugen1: Intersil Prism2.x or Atmel WLAN, rev 1.10/1.32, addr 2
[...]
uaudio0: Creative USB Audio, rev 1.10/1.00, addr 5
uaudio_add_selector: NOT IMPLEMENTED
uaudio0: audio rev 1.00
pcm0: <USB Audio> on uaudio0
pcm0: chn_init(pcm0: play:0) failed: err = 19
pcm0: pcm_chn_create(ua_chan, 1, 0xc21e1580) failed
[...]

The system on which I use FreeBSD is a Gericom X5 Force notebook that
uses a VIA chipset.