PCM mixer control does not affect output volume

In both Lucid and Maverick, there is a PCM mixer volume control present on my HDA ATI SB, which does not affect output volume.
PA merges it, so there is a risk for volume range anomalies.
It is not listed in the codec proc file, so how and why is it created?

ProblemType: Bug
DistroRelease: Ubuntu 10.10
Package: alsa-base 1.0.23+dfsg-1ubuntu2
ProcVersionSignature: Ubuntu 2.6.35-19.25-generic 2.6.35.3
Uname: Linux 2.6.35-19-generic x86_64
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.23.
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: david 2664 F.... pulseaudio
 /dev/snd/controlC1: david 2664 F.... pulseaudio
Card0.Amixer.info:
 Card hw:0 'SB'/'HDA ATI SB at 0xfe024000 irq 16'
   Mixer name : 'Realtek ALC888'
   Components : 'HDA:10ec0888,1458e601,00100001'
   Controls : 39
   Simple ctrls : 21
Card1.Amixer.info:
 Card hw:1 'Juli'/'ESI Juli@ at 0xcf00, irq 21'
   Mixer name : 'ICE1724 - multitrack'
   Components : ''
   Controls : 36
   Simple ctrls : 14
Card2.Amixer.info:
 Card hw:2 'HDMI'/'HDA ATI HDMI at 0xfdffc000 irq 44'
   Mixer name : 'ATI R6xx HDMI'
   Components : 'HDA:1002aa01,00aa0100,00100100'
   Controls : 4
   Simple ctrls : 1
Card2.Amixer.values:
 Simple mixer control 'IEC958',0
   Capabilities: pswitch pswitch-joined penum
   Playback channels: Mono
   Mono: Playback [off]
Date: Fri Aug 27 09:35:53 2010
EcryptfsInUse: Yes
InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Alpha amd64 (20100826)
PackageArchitecture: all
ProcEnviron:
 LANG=sv_SE.utf8
 SHELL=/bin/bash
SourcePackage: alsa-driver
dmi.bios.date: 06/24/2009
dmi.bios.vendor: Award Software International, Inc.
dmi.bios.version: F2
dmi.board.name: GA-MA770T-UD3P
dmi.board.vendor: Gigabyte Technology Co., Ltd.
dmi.board.version: x.x
dmi.chassis.type: 3
dmi.chassis.vendor: Gigabyte Technology Co., Ltd.
dmi.modalias: dmi:bvnAwardSoftwareInternational,Inc.:bvrF2:bd06/24/2009:svnGigabyteTechnologyCo.,Ltd.:pnGA-MA770T-UD3P:pvr:rvnGigabyteTechnologyCo.,Ltd.:rnGA-MA770T-UD3P:rvrx.x:cvnGigabyteTechnologyCo.,Ltd.:ct3:cvr:
dmi.product.name: GA-MA770T-UD3P
dmi.sys.vendor: Gigabyte Technology Co., Ltd.