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

[Yang, Libin]

Hi Raymond,

From: Raymond Yau [mailto:superquad.vortex2 at gmail.com]
Sent: Monday, August 10, 2015 12:23 PM
To: Yang, Libin
Cc: alsa-devel at alsa-project.org; Takashi Iwai; Lin, Mengdong; intel-gfx at lists.freedesktop.org
Subject: RE: [alsa-devel] [PATCH 3/4] ALSA: hda - display audio call ncts callback


2015-8-10 上午11:15於 "Yang, Libin" <libin.yang at intel.com<mailto: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

This is what we are thinking currently. Different companies

have different implementation. On currently Intel platforms,

it may show several pin widgets and each pin widget has

several device entry. But it actually only support 3 streams.

Mengdong is thinking to use dynamic PCM to implement it,

and so we don’t need each subdevice for each device entry.

I’m not sure we will use what solution. It seems it is a

good open question to discuss.

Regards,
Libin



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.