Re: ALSA USB quirk mixer driver question

[Takashi Iwai <tiwai@suse.de>]

On Thu, 27 Feb 2025 00:15:01 +0100,
Lena wrote:
> 
> Thanks for the reply!
> 
> So, if i understand correctly, instead of going through
> sound/usb/mixer_quirks.c, i need to create a standalone USBHID driver
> that exposes the ALSA kcontrols and then the ALSA userspace
> understands that it's the same interface and 'links' the
> UAC/isochronous audio part and the standalone ALSA mixer kcontrol part
> that has the volume knobs, mute, output select and input
> impedance/phantom power/headphone gain switches such that an userspace
> application (like alsamixer) treats it all as a single thing.

Well, how to manage HID device is other question.  Usually a HID
device provides the controls via input device API.  It's not
prohibited to use a sound API (in this case you'd need to create your
own sound card object), though.

> Does this driver then belong in sound/usb/ (given it imports the API
> in <sound/control.h>) or somewhere else (e.g. drivers/hid/usbhid/,
> drivers/usb/)?

Not likely.  It'll be a pure HID driver.


HTH,

Takashi