vc4.ko brings unusable&unstable ALSA sinks

[Diederik de Haas]

Hi,

On woensdag 31 maart 2021 09:31:03 CEST Ryutaroh Matsumoto wrote:
> > Is that a 32bit or 64bit kernel? AFAIK, all the problems are with 64bit.
> It's 64-bit.

Thx

> It is funny that 32-bit kernel works fine while 64-bit doesn't...

AFAIK, the GPU (VC4 in my case) is 32-bit, so that means (something like) 
architecture translation work on 64-bit systems, which isn't needed when 
everything is 32-bit.

> I am pretty sure that vc4hdmi does not work in the same way as
> snd_bcm2835.ko, as most of aplay commands fail with vc4hdmi
> while they succeed with snd_bcm2835.

My (naive?) assumption was that the latter has 'snd' in it's name, so if I 
want(ed) to do sth with sound, I needed that one.
But then the question arose "what is vc4hdmi for then?" It didn't seem to work 
to play audio normally/properly and it was sometimes loaded first, but not 
consistently, messing up index numbers. I later learned (IIUC) that it only 
works with IEC958 frames and that you need pulseaudio to deal with that 
properly.
While I first wanted to get rid of vc4hdmi, it now appears I should go with 
that one. But that's only based on our trial-and-error, not on any insight I 
could find online or from this ML.

> On my RPi4 with module_blacklist=snd_bcm, I have the following multi-channel
> capable output:
> 
> $ LANG=C.UTF-8 pacmd list-cards
> ...
> In the above "active profile: <output:iec958-stereo>" indicates the
> default is not multichannel. I believe that the default can be changed to
> the multichannel by (from pulse-cli-syntax(5)):

Yep, the one with the highest priority gets selected by default, but I changed 
that with "pactl set-card-profile 1 output:iec958-ac3-surround-51". That's why 
my "Active Profile" was different. I think pavucontrol is only or mostly a GUI 
around pactl/pacmd. You can also install just pavucontrol (on rpi-mpd) and 
run: "env PULSE_SERVER=rpi-mpd pavucontrol" (you need to enable some network 
settings for that to work though).
But I just realized that it's 'only' 5.1, not 7.1 ...

> Best regards, Ryutaroh
Cheers,
  Diederik
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 833 bytes
Desc: This is a digitally signed message part.
URL: <http://lists.infradead.org/pipermail/linux-rpi-kernel/attachments/20210331/0bb34853/attachment.sig>