[alsa-devel] [PATCH 0/3] ALSA: usb channel map fixes

Takashi Iwai tiwai at suse.de
Tue Nov 5 07:50:47 CET 2013

At Tue,  5 Nov 2013 04:41:05 +0100,
David Henningsson wrote:
> Ok, so I actually tested my patch, and it turned out things were slightly
> more complex than expected - the original patch is still needed, but in addition,
> we also need to build the channel map after the format parse, because the format
> of the descriptor is not always the same as the format of the input terminal.
> These two fixes made the mono chmap show up on my logitech USB headset, on both
> output and input side.
> I also tested my patches with another USB device. This device is UAC2, and when
> looking at lsusb I found that in UAC2 the streaming descriptor has a channel config too.
> Given what I found on the headset, it seems reasonable to use this channel config
> instead of the input terminal's channel config, although in my case it made no
> practical difference.
> David Henningsson (3):
>   ALSA: usb: supply channel maps even when wChannelConfig is
>     unspecified
>   ALSA: usb - For class 2 devices, use channel map from altsettings
>   ALSA: usb - Don't trust the channel config if the channel count
>     changed

Thanks, applied all patches now.


>  sound/usb/stream.c |   29 +++++++++++++++++++++--------
>  1 file changed, 21 insertions(+), 8 deletions(-)
> -- 

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