FreeBSD on Older Laptops: Sound

FreeBSD version: 9.3
Device: HP EliteBook 6930p
Symptom: No sound although no error messages, and truss shows /dev/dsp being written to normally

The usual cause of this issue is that wrong pins are allocated to the sound output. Pin dumping using the following commands can help find the root cause [1].

# sysctl dev.hdac.0.pindump=1
# dmesg

For HP EliteBook 6930p, the following lines have to be added to /boot/device.hints file:

/boot/device.hints:

# From the web for sound
hint.hdac.0.cad0.nid22.config="as=1"
hint.hdac.0.cad0.nid18.config="as=2"

[1]: http://forums.pcbsd.org/showthread.php?t=15377