[RFC PATCH 01/14] ASoC: Add SOC USB APIs for adding an USB backend

[Greg KH]

On Fri, Dec 23, 2022 at 03:31:47PM -0800, Wesley Cheng wrote:
> diff --git a/sound/soc/soc-usb.c b/sound/soc/soc-usb.c
> new file mode 100644
> index 000000000000..c6c376960e4d
> --- /dev/null
> +++ b/sound/soc/soc-usb.c
> @@ -0,0 +1,66 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2022 Qualcomm Innovation Center, Inc. All rights reserved.
> + */
> +#include <linux/usb.h>
> +#include <sound/soc.h>
> +#include <sound/soc-usb.h>
> +#include "../usb/card.h"
> +
> +struct snd_soc_usb *ctx;

Note, this will not work.  You can not only have "one" state for a
system like this.  That just broke any system with more than one
controller, of which we have millions.

This has to be dynamic for any number of controllers in the system, like
the sound and USB core can handle.  Any requirement of "there can be
only one!" will obviously never be acceptable as that is not how Linux
works.

thanks,

greg k-h