[alsa-devel] [RFC] Fix for conflict of HDMI and SPDIF IEC958 controls

[Takashi Iwai]

At Mon, 15 Oct 2012 12:09:40 +0200,
David Henningsson wrote:
> 
> On 10/12/2012 05:18 PM, Takashi Iwai wrote:
> > Hi,
> >
> > there is a long-standing problem in HD-audio regarding IEC958
> > controls.  When both an SPDIF and an HDMI are created on the same
> > card (e.g. one from analog codec and one from graphics chip), the
> > driver assigns the IEC958 controls just with new indices, 0, 1, 2...
> >
> > The problem is that there is no way to connect between this index and
> > the actual PCM device.  Currently, alsa-lib HDA-Intel.conf has a fixed
> > configuration:
> >    spdif  -> IEC958 xxx index=0, PCM dev=1
> >    hdmi,0 -> IEC958 xxx index=0, PCM dev=3
> >    hdmi,1 -> IEC958 xxx index=1, PCM dev=7
> >    hdmi,2 -> IEC958 xxx index=2, PCM dev=8
> >    hdmi,3 -> IEC958 xxx index=3, PCM dev=9
> >
> > So obviously spdif and the first hdmi conflict.
> 
> If these mixer controls need to be set to specific value for 
> playback/capture to work, why isn't this logic handled entirely in 
> kernel space in the first place?
> 
> I e, instead of relying on alsa-lib to setup "IEC958 Playback Default" 
> correctly for us, we always do what setting "IEC958 Playback Default" 
> would have done, but in the kernel directly instead.

Hm, I don't get your point.  Could you elaborate?


Takashi