Re: [PATCH v21 27/39] ASoC: Introduce SND kcontrols to select sound card and PCM device

From: Pierre-Louis Bossart
Date: Wed May 08 2024 - 09:18:59 EST




On 5/7/24 14:51, Wesley Cheng wrote:
> Add SND kcontrol to SOC USB, which will allow for userpsace to determine
> which USB card number and PCM device to offload. This allows for userspace
> to potentially tag an alternate path for a specific USB SND card and PCM
> device. Previously, control was absent, and the offload path would be
> enabled on the last USB SND device which was connected. This logic will
> continue to be applicable if no mixer input is received for specific device
> selection.
>
> An example to configure the offload device using tinymix:
> tinymix -D 0 set 'USB Offload Playback Route Select' 1 0
>
> The above command will configure the offload path to utilize card#1 and PCM
> stream#0.

I don't know how this is usable in practice. Using card indices is
really hard to do, it depends on the order in which devices are
plugged-in...