[alsa-devel] HDMI LPE audio on Intel Compute Stick 2nd Gen (CHT)

[Takashi Iwai]

On Sun, 22 Oct 2017 15:00:12 +0200,
Ian W MORRISON wrote:
> 
> On 21 October 2017 at 03:53, Takashi Iwai <tiwai at suse.de> wrote:
> 
> > On Fri, 20 Oct 2017 17:54:45 +0200,
> > Pierre-Louis Bossart wrote:
> > >
> > > On 10/20/17 8:45 AM, Ian W MORRISON wrote:
> > > >> I've just noticed that non of the kernels from v4.13 and up run on my
> > > >>> Intel Compute Stick (2nd gen Cherry Trail STK1AW32SC) unit and have
> > > >>> HDMI LPE audio working.
> > > >>>
> > > >>
> > > >> I have not tested HDMI in a while but I am not aware of any issues
> > either.
> > > >> There were some patches recently to fix PulseAudio problems and I
> > suppose
> > > >> some folks used a recent kernel?
> > > >>
> > > >>
> > > > It actually happened since v4.12 as now I get three HDMI LPE Audio
> > devices
> > > > show up with 'aplay -l' rather than just one. Only 'device 2' works so
> > if I
> > > > change the sink to use that device I get sound. So basically it can be
> > > > fixed in userland however I'm seeing others with different devices also
> > > > complaining how audio is broken and I think it is something that many
> > users
> > > > don't know to fix. Is it worth looking into further or just leaving it
> > as a
> > > > known issue?
> > >
> > > I don't think it's a bug, it's a feature...
> > > The jack information tells you which device is connected/active, so
> > > userspace has all the data needed to select the right routing.
> >
> > Right, it's a new feature that was recently added, for supporting
> > multiple HDMI/DPs.  The latest PA should be able to check the jack
> > detection of each port, so that it can switch to the actually
> > connected one.
> >
> >
> > Takashi
> >
> 
> Thanks for the explanation. The PA package for Ubuntu is a bit behind (v8
> for 16.04 LST and v10 for latest 17.10) so it will be easier for users just
> to edit /etc/pulse/default.pa in the interim. But is there a way to stop
> the multiple and repeating "Audio Port: ASoC: no backend DAIs enabled for
> Audio Port" messages in dmesg from occurring without modifying the distro's
> kernel?

The DAI backend has nothing to do with HDMI LPE audio.  It's from ASoC
Intel SST driver.  You need to set up the routing either via UCM or
manually.


Takashi