[alsa-devel] [PATCH] New quirk for USB DAC 08bb:2704

[Takashi Iwai]

At Mon, 14 Feb 2011 21:16:18 +0000,
Omari Stephens wrote:
> 
> On 02/14/2011 05:10 PM, Takashi Iwai wrote:
> > At Sat, 12 Feb 2011 22:53:25 +0000,
> > Omari Stephens wrote:
> >>
> >> Howdy, all
> >>
> >> I have one of these:
> >> http://www.chordelectronics.co.uk/products_detail.asp?id=63
> >>
> >> It's got one of these USB DACs inside
> >> ID 08bb:2704 Texas Instruments Japan
> >>
> >> The DAC has a single mixer control, Master, which allows you to adjust
> >> volume and mute/unmute.  The fun thing is that the volume adjustment has
> >> no effect whatsoever.  On machines running pulse, this means that output
> >> will be at 0dB pretty much all the time.  (Of course, this is true of
> >> non-pulse machines also).
> >>
> >> The attached patch disables the Master control, which causes pulse to
> >> control levels entirely in software, as it should for this device.
> >>
> >> The main downside to this patch is that, while the volume part of the
> >> Master control is non-functional, the mute/unmute aspect does work as
> >> expected.  I couldn't figure out how to change the Master control to
> >> just a mute/unmute control, but if someone has suggestions on what to
> >> do, that'd be appreciated.  Judging by the comments in the code (and
> >> contrary to what I wrote in the map comment), I presume the mute/unmute
> >> control is the only reason why 08bb:2702 isn't doing this same thing.
> >
> > The patch looks good to me.  Could you give your sign-off?
> Oops; sorry (haven't submitted a kernel patch before).  Will do.
> 
> That said, I have some friends with the same device, and at least one 
> says that the volume control works fine for him, so I want to do a bit 
> more investigation before this quirk gets added.  Will send email when I 
> get things figured out a little more.

OK, let me know if it's ready.


thanks,

Takashi