Hector Martin

That's at least a very simple patch.

Actually, I don't think channel swaps are a thing in the ALSA USB driver. Seems that's handled in userspace... which means only some userspace will handle it properly. Probably needs a separate PulseAudio config etc...

Okay, but it's an easy pa module *or* an easy kernel patch to add that entirely.

Forgive me, I've been guess-and-test debugging a terrible USB sound chip.

I think the kernel guys don't want audio format conversions in kernel space, so it's gotta be userspace.

Fair enough, I guess, though it's pretty arbitrarily given the existing quirk tables.

I think the point is the kernel shouldn't be doing format conversions, which have a high CPU cost. All the existing quirks are about metadata/control, not formats.

Hmm. Maybe. Still not seeing how it's less expensive to do the operation in userland. Outcome for the user is certainly better if we do it in kernel, just from less effort involved. If you want to backdoor this with hype, just add an ebpf hook with quirkable defaults.