[Pkg-alsa-devel] Sound Open Firmware support in Debian

[Pierre-Louis Bossart]

Hi,

On recent HDAudio- and SoundWire-based platforms, the use of SOF (Sound 
Open Firmware) is required to enable the DSP-based path. The Digital 
Microphone and SoundWire external components will just not be used 
otherwise.

Since we see quite a few issues related to configurations on 
debian-based platforms, I thought it'd be a good idea to try and engage 
directly with Debian maintainers to do the right thing.

a) I see that the testing and unstable versions use ALSA-lib 1.2.2.2 - 
which is good. The alsa-ucm-conf are all up-to-date as well - but they 
will only work with a kernel 5.5.8 and later. Changes were made to add 
information in the card component string. I believe bullseye/testing is 
only at version 5.4.19, so there is a disconnect here, these UCM files 
won't work since the information they rely on is not provided by the 
kernel. Only in sid/unstable do I see a kernel that will work. If 
bullseye/testing want to support SOF, we need to either backport kernel 
patches, or create different versions of the UCM files.

b) we have a long-standing issues that the firmware and topology files 
are not included in any debian package. All the SOF code is open, meets 
Debian requirements, but to run on most platforms the firmware needs to 
be signed by Intel with a 'production key', so for convenience, we 
provide a release with all necessary binaries included: 
https://github.com/thesofproject/sof-bin/tree/stable-v1.4.2

We will have in the coming week(s) a 1.5 release, and I'd like to work 
with the Debian team to start creating firmware packages. We can take 
the Ubuntu route, where they add all the firmware and topology to the 
linux-firmware packages, but it'd make more sense IMO to split this into 
firmware files, topology files and utilities for debug. I have 
absolutely zero experience in creating Debian packages, but all we need 
is really to install the files and create symlinks. Could I ask for 
feedback here on what Debian maintainers think?

c) going back to the kernel part, we maintain a list of kconfig options 
that are recommended and some that are just for developers: 
https://github.com/thesofproject/kconfig. I have zero experience as well 
with Debian kernel management, but I'd like to make sure the recommended 
options are selected and that somehow we remain in sync.

Thanks

-Pierre