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

[Ian W MORRISON]

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?