Setting the capture levels on the Line-In capture channel when using an ARX USB I/O sound card for recording and playback did not work properly. The set values were not persistent. With this update, the capture values are now cached in the usb-audio driver leaving the set capture levels unchanged.
Created attachment 479163[details]
2.6.18-238 based patch
Description of problem:
Customer is using ARX USB I/O[1] soundcards for recording/playback however they're unable to set the mixer levels on the Line-In capture channel. From alsamixer the capture levels cannot be adjusted, and when adjusted from gnome-volume-control the settings do not persist. Using amixer we can see that the levels are not being set properly:
# amixer --debug -c 0 set PCM,0 25% cap
Simple mixer control 'PCM',0
Capabilities: cvolume cswitch cswitch-joined
Capture channels: Front Left - Front Right
Limits: Capture 0 - 128
Front Left: Capture 32 [25%] [5.58dB] [on]
Front Right: Capture 32 [25%] [5.58dB] [on]
# amixer --debug -c 0 get PCM,0
Simple mixer control 'PCM',0
Capabilities: cvolume cswitch cswitch-joined
Capture channels: Front Left - Front Right
Limits: Capture 0 - 128
Front Left: Capture 1 [1%] [0.00dB] [on]
Front Right: Capture 1 [1%] [0.00dB] [on]
jkysela pointed me to upstream commit:
http://git.alsa-project.org/?p=alsa-kernel.git;a=commit;h=641b4879444c0edb276fedca5c2fcbd2e5c70044
..which caches mixer values in the usb-audio driver. I've built a test kernel (2.6.18-238 + this patch) which has been confirmed to resolve the issue:
https://brewweb.devel.redhat.com/taskinfo?taskID=3114025
Attaching backported patch which applies against 2.6.18-238.
Version-Release number of selected component (if applicable):
2.6.18-238.el5
How reproducible:
always
Steps to Reproduce:
1. amixer --debug -c 0 set PCM,0 25% cap
2. amixer --debug -c 0 get PCM,0
Actual results:
capture levels unchanged
Expected results:
capture levels adjusted
Additional info:
[1] http://www.arx.com.au/International/audibox_usb_io.htm
in kernel-2.6.18-246.el5
You can download this test kernel (or newer) from http://people.redhat.com/jwilson/el5
Detailed testing feedback is always welcomed.
Technical note added. If any revisions are required, please edit the "Technical Notes" field
accordingly. All revisions will be proofread by the Engineering Content Services team.
New Contents:
Setting the capture levels on the Line-In capture channel when using an ARX USB I/O sound card for recording and playback did not work properly. The set values were not persistent. With this update, the capture values are now cached in the usb-audio driver leaving the set capture levels unchanged.
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.
http://rhn.redhat.com/errata/RHSA-2011-1065.html