[alsa-devel] [PATCH 3/4] ALSA: hda - display audio call ncts callback

[Raymond Yau]

2015-8-10 上午11:15於 "Yang, Libin" <libin.yang at intel.com>寫道：
>
> Hi Raymond,
>
> >
> > > >     }
> > > >
> > > > +   if (is_haswell_plus(codec)) {
> > > > +           if (acomp && acomp->ops && acomp->ops->set_ncts)
> > > > +                   acomp->ops->set_ncts(acomp->dev, per_pin-
> > > >pin_nid - 4,
> > >
> > > Please describe more how "pin_nid - 4" is supposed to work.  Also...
> >
> > OK, I see.
> >
> > >
> > > > +                           0, runtime->rate);
> > >
> > > ... this implies that no MST support included?
> >
> > We will support MST later. Currently I just add the
> > interface to support MST, but not implementing it.
> Refer to DCN HDA040-A
> Multi-stream over Single Display Port
> Can the driver use subdevices for those display port support multi
streaming ?
>
> [Libin] What do you mean subdevice here,
> using a struct device to represent a dev_entry or an int type?

http://git.kernel.org/cgit/linux/kernel/git/tiwai/hda-emu.git/tree/codecs/stac9227-intel-d946gzis-mobo?id=HEAD

When HDA codecs have three Audio Input widgets, the driver create three
subdevices for those desktop which have three or more input sources in the
past

ARECORD

**** List of CAPTURE Hardware Devices ****
card 0: Intel [HDA Intel], device 0: STAC92xx Analog [STAC92xx Analog]
  Subdevices: 3/3
  Subdevice #0: subdevice #0
  Subdevice #1: subdevice #1
  Subdevice #2: subdevice #2

With the auto generic parser , the driver create one subdevice for Analog
two subdevices for Alt Analog

**** List of CAPTURE Hardware Devices ****
card 0: Intel [HDA Intel], device 0: STAC92xx Analog [STAC92xx Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: Intel [HDA Intel], device 2: STAC92xx Alt Analog [STAC92xx Alt
Analog]
  Subdevices: 2/2
  Subdevice #0: subdevice #0
  Subdevice #1: subdevice #1

>
> The specification allow up to 64 device entries
> This mean the number of subdevices is equal to the device list length
> More than one audio output /converters can be connected to the multi
stream displayport pin widget but different device entry while only one
audio output can be dynamically allocated  to other HDMI pin widget
>
> [Libin] Yes, Pin widget can have multiple device entry and connecting
different converters. The audio output will be based on device entry.