docs/155264: [handbook] Extend "7.2.2.1 Common Problems" with hw.snd.default_unit=n

[Martin Ziegler]

>Number:         155264
>Category:       docs
>Synopsis:       [handbook] Extend "7.2.2.1 Common Problems" with hw.snd.default_unit=n
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-doc
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          update
>Submitter-Id:   current-users
>Arrival-Date:   Fri Mar 04 13:00:23 UTC 2011
>Closed-Date:
>Last-Modified:
>Originator:     Martin Ziegler
>Release:        8.2-RELEASE
>Organization:
>Environment:
-
>Description:
Current graphic cards from ATI and Nvidia are often equipped with there own sound devices. Often these devices get lower device numbers (pcm*) than the actual sound card:
> dmesg
..
hdac0: HDA Driver Revision: 20100226_0142
hdac1: HDA Driver Revision: 20100226_0142
hdac0: HDA Codec #0: NVidia (Unknown)
hdac0: HDA Codec #1: NVidia (Unknown)
hdac0: HDA Codec #2: NVidia (Unknown)
hdac0: HDA Codec #3: NVidia (Unknown)
pcm0: <HDA NVidia (Unknown) PCM #0 DisplayPort> at cad 0 nid 1 on hdac0
pcm1: <HDA NVidia (Unknown) PCM #0 DisplayPort> at cad 1 nid 1 on hdac0
pcm2: <HDA NVidia (Unknown) PCM #0 DisplayPort> at cad 2 nid 1 on hdac0
pcm3: <HDA NVidia (Unknown) PCM #0 DisplayPort> at cad 3 nid 1 on hdac0
hdac1: HDA Codec #2: Realtek ALC889
pcm4: <HDA Realtek ALC889 PCM #0 Analog> at cad 2 nid 1 on hdac1
pcm5: <HDA Realtek ALC889 PCM #1 Analog> at cad 2 nid 1 on hdac1
pcm6: <HDA Realtek ALC889 PCM #2 Digital> at cad 2 nid 1 on hdac1
pcm7: <HDA Realtek ALC889 PCM #3 Digital> at cad 2 nid 1 on hdac1
..

As a result, the user need to set hw.snd.default_unit  other than 0 (e.g. to 4 in the above example).


>How-To-Repeat:
-
>Fix:
Add a section about hw.snd.default_unit=n in the handbook, section "7.2.2.1 Common Problems"

>Release-Note:
>Audit-Trail:
>Unformatted: