[alsa-devel] [PATCH] USB-Audio: Disable "Logitech USB Headset" iec958 device

Clemens Ladisch clemens at ladisch.de
Thu Mar 8 16:47:31 CET 2012

David Henningsson wrote:
> Because Logitech USB Headsets do not have any digital devices,
> prevent them from being opened. This simplifies probing the
> device in PulseAudio.
> --- a/src/conf/cards/USB-Audio.conf
> +++ b/src/conf/cards/USB-Audio.conf
> @@ -36,6 +36,8 @@ USB-Audio.pcm.surround40_type {
>  # number for the iec958 device can be changed here.
>  USB-Audio.pcm.iec958_device {
>  	# "NoiseBlaster 3000" 42
> +	# Make sure we can't open this device digitally, because it does not exist
> +	"Logitech USB Headset" 999
>  }

This introduces a blacklist of devices that do not have digital outputs.
There are lot of other such devices that need such entries to make PA
work better, but at the moment, the only alternative would be a whitelist
of devices with digital outputs, which would have exactly the same
maintenance problems.

As long as there is no mechanism for .conf files to find out whether
a USB device actually has digital outputs, there's no better way to
solve the problem.


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