[alsa-devel] Problems with the DP MST audio support patchset

[Pascal Wichmann]

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Hi all,

> I guess the digital-7.1 corresponds to HBR, and it's a special 
> setup. Meanwhile 5.1 output he has tried is likely the LPCM, so
> both are in a completely differently manner.
Thank you, that sounds like a good explanation for my first issue.


For the other problem, that seems to be some kind of HDMI handshake
related issue to me.
I have done some more research and found similar
problems like [0]. Their solution to enable a pulseaudio loopback seemed
to improve the situation at first; at least during the last two hours,
the problem did not occur as often as it did before (without explicitly
provoking it), but it occurred though.

In addition, I have disabled the power save options of the snd_hda_intel
module:
> options snd_hda_intel power_save=0 power_save_controller=N
This however does not seem to have any impact on the problem at all.

I have also found a way to reliably reproduce the problem by muting and
immediately unmuting the output in alsamixer having some audio running
- -- this way, the output gets silenced for a few seconds a moment after
the unmuting almost always.

Is the above solution using the pulseaudio loopback module not enough to
prevent handshake issues? Do handshake issues sound suitable at all? Do
you have any other ideas where the problem may lies?


Regards,
Pascal

[0]
https://ubuntuforums.org/showthread.php?t=2215224&p=13117108#post1311710
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