[alsa-devel] [RFC PATCH 0/3] support DP MST audio

[Takashi Iwai]

On Mon, 26 Sep 2016 10:35:35 +0200,
libin.yang at linux.intel.com wrote:
> 
> From: Libin Yang <libin.yang at linux.intel.com>
> 
> This patchset starts to support DP MST audio.
> 
> This patchset is based on drm-intel-nightly on
> git://anongit.freedesktop.org/drm-intel
> 
> Libin Yang (3):
>   ALSA: hda - codec add DP MST support for connection list
>   ALSA: hda - add DP mst verb support
>   ALSA: hda - add DP mst audio support

I read the patchset again, and I'm still not convinced enough by this
change.

The connection list is coded in the current way under the assumption
that connections are more or less static.  The connections are cached
in snd_array, which is only for growing up, and not suitable for the
entries that might be frequently removed.  The removal is done only at
overriding, and it happens only once at boot.

OTOH, with DP-MST case, the connection list is basically dynamic.  It
may increase or decrease depending on the connected monitors...  Is my
understanding correct?  Or is the DP-MST connection list is static,
too?  Then I do wonder how it covers the whole connections with
arbitrary device indices.

So, the connection cache management is one thing.  Another thing is
that the patchset doesn't consider about the pin ELD notification.
Basically we switched to ELD notification instead of the pin unsol
event for Intel chips.  How does it fit?


thanks,

Takashi