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

[Raymond Yau]

2012-10-15 下午3:46 於 "Takashi Iwai" <tiwai at suse.de> 寫道：
>
> At Mon, 15 Oct 2012 10:31:50 +0800,
> Raymond Yau wrote:
> >
> > 2012-10-12 下午11:19 於 "Takashi Iwai" <tiwai at suse.de> 寫道：
> > >
> > > 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.
> > >
> > > Basically this can be fixed by reassigning each IEC958 control with
> > > the same device number corresponding to the PCM device.  That is, for
> > > SPDIF, assign a control element with device=1, for HDMI,
> > > device=3,7...
> > > However, this obviously breaks the old configuration unless user
> > > upgrades the alsa-lib configuration.  Thus this is no-go.
> > >
> > > Now here is a compromise: the IEC958 control for SPDIF is reassigned
> > > to device=1 *only* when SPDIF and HDMI coexist.  Since the
> > > configuration is anyway broken as is now in such a case, it's no big
> > > deal to fix one side in an incompatible way.  (The reason why SPDIF
> > > is re-assigned is that I guess majority of user require more HDMI than
> > > SPDIF in such a configuration.)
> > >
> > > In addition, we need a fix in alsa-lib.  Also not for breaking the
> > > compatibility with older kernel, we need some fallback check.  I did a
> > > quick hack to alsa-lib conf code and added "skip_rest" option to the
> > > hook element, so that only the first matching element is taken.
> >
> > how about those hdmi jack and iec958 on ad1989b?
>
> On AD codecs, all digital outputs are exposed as a single cloned
> device with HDA_PCM_TYPE_SPDIF.

how about ad1988b with nvidia codec ?

from user point of view , how can they differenitate hdmi jack is digital
ouput and hdmi output ?

https://bugs.launchpad.net/ubuntu/+source/pulseaudio/+bug/881826

**** List of PLAYBACK Hardware Devices ****
card 0: NVidia [HDA NVidia], device 0: AD198x Analog [AD198x Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: NVidia [HDA NVidia], device 1: AD198x Digital [AD198x Digital]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: NVidia [HDA NVidia], device 3: HDMI 0 [HDMI 0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0