[alsa-devel] DP1.2 MST audio support discussion

[Yang, Libin]

Hi,

> -----Original Message-----
> From: Takashi Iwai [mailto:tiwai at suse.de]
> Sent: Friday, October 16, 2015 2:38 PM
> To: Raymond Yau
> Cc: Yang, Libin; ALSA Development Mailing List; airlied at linux.ie; Lin,
> Mengdong; Girdwood, Liam R; tanuk at iki.fi; David Henningsson
> Subject: Re: [alsa-devel] DP1.2 MST audio support discussion
> 
> On Fri, 16 Oct 2015 02:32:50 +0200,
> Raymond Yau wrote:
> >
> > > >
> > > > Do it mean that only one DP MST port and no HDMI port on the
> same
> > graphic
> > > > card ?
> > >
> > > No.
> >
> > If there is only one HDMI and one Display Port, this mean that there
> are
> > two pin complexes
> 
> Yes, and the mapping doesn't change in this case as before.
> 
> > How about the name of jack detection kctl of three Display Port
> monitors
> > which are created on the same pin complex but different dev_index ?
> 
> It's one of the models we've considered.  Basically the number of
> devices can be up to 64 (or such) per pin.  For Intel case, due to the
> limitation of converters, it's up to 3.  For other GPUs that may drive
> more simultaneous outputs, the number increases in square.  If a GPU
> may handle 16 outputs, it'll be 256 entries.
> 
> Although the 256 entries are certainly manageable as kctl, whether
> this is the best representation for user-space is a question.
> 
> > Will three three display port monitor playback devices always play
> > different stream even when the displays are in clone mode ?
> 
> The clone mode is another messy part...

After checking internally, we will not support clone mode atm based
on the HW suggestion.

> 
> > > > If DP MST are dasiy chained, the unplug of the first monitor from
> > Display
> > > > Port will cause all DP monitor in the dasiy chain disconnect
> > >
> > > Yes.
> > >
> >
> > Do the power off of the Display Port in the middle of the dasiy chain
> also
> > affect the last display port mointor in the dasiy chain ?
> 
> Possibly.  But it's not what we really care, as this is the thing the
> graphics side should handle.
> 
> 
> Takashi