From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Mack Subject: Re: How to create an Alsa mixer for a USB device w/o mixer descriptor? Date: Wed, 17 Mar 2010 17:11:16 +0100 Message-ID: <20100317161116.GG30801@buzzloop.caiaq.de> References: <4BA094B9.8010907@web.de> <20100317112804.GB30801@buzzloop.caiaq.de> <4BA0C162.5090606@web.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from buzzloop.caiaq.de (buzzloop.caiaq.de [212.112.241.133]) by alsa0.perex.cz (Postfix) with ESMTP id 11D55103841 for ; Wed, 17 Mar 2010 17:11:22 +0100 (CET) Content-Disposition: inline In-Reply-To: <4BA0C162.5090606@web.de> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: alsa-devel-bounces@alsa-project.org Errors-To: alsa-devel-bounces@alsa-project.org To: Felix Homann Cc: alsa-devel@alsa-project.org List-Id: alsa-devel@alsa-project.org On Wed, Mar 17, 2010 at 12:47:46PM +0100, Felix Homann wrote: > Daniel Mack schrieb: > >Does that mean it doesn't export _any_ descriptors for that? Or just not > >output terminal? > > > > As far as I can tell, there really is no descriptor for a mixer > device or similar. Please, see the attached output of lsusb -v. (The > device is mostly working with QUIRK_AUDIO_STANDARD_INTERFACE quirks. > ) Jep, it seems so. > Although I posted it before, you might take a look at my findings in > the attached reverse-engineering-...txt file. I didn't know > anything about Audio Class devices when I gathered that information, > and digged only a bit deeper by now. For me, it seems that the > device is actually operated like an ordinary USB mixer (v1). Well then I would just try it that way and see what it takes. > >Thinking about what you're trying to achieve, I think at least one way > >to go is to implement a new function ('handle_audio_mixer_unit_quirks' > >for example) in sound/usb/mixer_quirks.c and call it from > >snd_usb_create_mixer(). The function would need to return a static fake > >descriptor, hard-coded in mixer_quirks.c. Now that the driver works with > >structs for descriptors, that shouldn't be hard to do. > > OK, I'll try to work my way through the sources. Although it's > probably not too hard for someone familiar with Alsa and USB > devices, it might take some time for me ;-) It is, however, easier to implement such changes if you actually have the device to play around with it than trying to add such quirks blindly. So - go, give it a try :) Daniel