[Freedreno] hdmi audio on ifc6410

[Rob Clark]

On Wed, Dec 11, 2013 at 8:08 PM, Rob Clark <robdclark at gmail.com> wrote:
> fyi, I've managed to get hdmi audio (mostly) working, on the inforce
> board.  I expect that basically the same thing should work on bstem as
> well.
>
> I've untangled the msm alsa/soc driver from ION and fixed a few issues
> with it along the way.  What I have is still a bit work-in-progress,
> but I've pushed to here:
>
>   https://github.com/freedreno/kernel-msm/commits/ifc6410-drm-hdmi-audio
>   git://github.com/freedreno/kernel-msm.git ifc6410-drm-hdmi-audio
>
> (and may I add, the sound/soc/msm stuff is a royal PITA to debug!)
>
> There are a couple rough edges:
>
> 1) Shows up as 'Analog Output' in gnome sound control panel.. I'm not
> much of an audio expert but I think this is a symptom of pulseaudio
> not properly recognizing things.  Maybe we need some pulseaudio config
> files so that it properly understands the audio routing options?

fwiw, it seems like what we need is UCM config:

http://www.alsa-project.org/main/index.php/Use_Case_Manager

looks like pulseaudio already supports UCM, so I think once we get the
proper UCM config so that userspace can properly understand all the
audio routing/mixing options, things should just work:

http://www.freedesktop.org/wiki/Software/PulseAudio/Notes/3.0/

BR,
-R

> 2) Glitch at beginning of playback.. probably I need to do something
> to synchronize w/ audio engine before enabling audio packets on the
> hdmi side of things.  Need to sort out how that works.
>
>
> for folks who want to try it out, I've also put a pre-built kernel here:
>
>   http://people.freedesktop.org/~robclark/f20/ifc6410-boot-audio.img
>
> and my alsa config:
>
>   http://people.freedesktop.org/~robclark/f20/asound-hdmi.state
>
> to apply my config on your board:
>
>   sudo alsactl restore -f asound-hdmi.state
>
> If you know anything about SoC audio + pulseaudio, I could certainly
> use some help sorting out the audio configuration/routing mess.. it's
> something pretty far outside of my area of expertise.
>
> BR,
> -R