DCP audio

[povik]

(This is early driver code aimed at developers and competent testers.)

Depends on AsahiLinux/m1n1#286.

This has work-in-progress SIO driver, DCP audio bits, and devicetree additions on t8103. It demonstrates playback over HDMI on M1 Mac mini.

What should work (on M1 Mac mini)

• Advertising the available sample rates and formats
• Hotplug (with a jack state visible to userspace); but maybe it's broken, I haven't thoroughly tested this.
• Playback

Rough edges

• The driver has only ever seen stereo channel layouts, though it has code to parse and select other non-trivial layouts which is based on some guesswork. We will see how it performs.
• I have seen occasions of SIO failing to boot, or failing to receive its boot-up parameters. This is an open issue, I am not sure about its cause.

Tools

• You can use this script to dump the blob by which the DCP describes the available sound modes. You run the script in userspace under a kernel built from this tree. I am curious to see the blob in conjunction with various displays supporting fancy sound modes. Sample output You need to open the PCM device once before the blob can be dumped.

[jannau]

This should now be available in asahi-wip / asahi-6.8.8-1 and supported on all devices except M2 Ultra based ones. The boot issue is understood and fixed.

[povik]

I suppose we can close this.

[jannau]

I did not close it since the link to your script might become useful. Thanks for the feature and sorry that it took so long to integrate.

[povik]

sorry that it took so long to integrate.

Not at all, me not being active recently could be to blame too. Anyway thanks for integrating it!