[alsa-devel] sof/hda rework to share more of patch_hdmi.c logic

[Takashi Iwai]

On Thu, 15 Aug 2019 16:28:02 +0200,
Kai Vehmanen wrote:
> 
> Hi Takashi,
> 
> I notice you are doing a lot of cleanups to HDA code. Just FYI I'm looking 
> into modifying the SOF Intel backend to use 
> snd-hda-codec-hdmi/patch_hdmi.c for HDMI/DP audio support, i.e. to be able 
> to share this code between snd-hda-intel and SOF Intel (and not using 
> hdac-hdmi).
> 
> Let me know if this clashes with something you are already looking into. I 
> have a very rough version up and running, but it still needs some work. If 
> the general idea seems ok to you, I'll continue to work on a RFC patch and 
> send for review.

That sounds like a good idea.

Currently I've almost done for HD-audio rework for 5.4, so feel free
to go ahead.

> This will change how HDMI is exposed to user-space with SOF Intel drivers, 
> so we need to be extra careful how this is introduced. But this really 
> seems to be the best way to go to avoid the duplicated maintenance work 
> with two drivers that we now have.

Agreed.  I guess the biggest difference is the handling of the
DP-MST.  The legacy HD-audio HDMI driver takes a different approach
for DP-MST, namely, it chooses dynamically the pin that is connected
with a monitor.  It's for keeping the compatibility (more or less)
with old behavior; the program just needs to open the device that
corresponds to the notification via jack ctl without fiddling with
other extra routing.

> PS Tracked in SOF github as 
>    https://github.com/thesofproject/linux/issues/1123

OK, will watch out.


thanks,

Takashi