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From: Clemens Ladisch <clemens@ladisch.de>
To: Brent Weatherall <brentweatherall@gmail.com>
Cc: alsa-devel@alsa-project.org,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Subject: Re: Possible message repeat
Date: Wed, 13 Jun 2012 16:48:50 +0200	[thread overview]
Message-ID: <4FD8A852.1080502@ladisch.de> (raw)
In-Reply-To: <CAAo96ZB8WUuFyNm-GcLubh+uJ2v99-U_7uXFEtHBi638E=vWhw@mail.gmail.com>

Brent Weatherall wrote:
> I am trying to specify an extension to the UAC specification and then
> write a user space driver/application to use the extension when
> a device that supports it is available in Linux.
>
> Can anyone assist me with the best path forward for writing user space code
> to use the XU I am going to define?  Meaning generically speaking how to
> use UAC XU controls in ALSA.

XU controls cannot be used generically.  The driver must be extended to
create the vendor-specific controls of this particular device; or the
driver could get a function to allow userspace to add such controls.

> it appears that any XU controls would be processed through usbmixer.c,
> but I don't see how to use the code in usbmixer from user space.

That code creates mixer controls.

> And so far I can't tell what source usbmixer resides in.

sound/usb/mixer.c in the kernel source, although such extensions
probably belong into mixer_quirks.c.


Regards,
Clemens

  reply	other threads:[~2012-06-13 14:48 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-06-13 14:13 Possible message repeat Brent Weatherall
2012-06-13 14:48 ` Clemens Ladisch [this message]
     [not found] <CAAo96ZA3=A2cxTPR5Yegoaru88fKAJx277kdSqS+i9vJ8JA=tg@mail.gmail.com>
2012-06-25  9:49 ` Clemens Ladisch
2012-06-25 15:02   ` Brent Weatherall

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