I need to combine two HDSPe MADI FX cards to one virtual device. I have a working driver, which is alsa-compatible. I can select each single card in any alsa-compatible application and all channels work flawless.
For combining the MADI FX cards to one virtual device, I created an .asoundrc with 194 inputs for each card. When I start that virtual device via
jackd -R -d alsa -C madifx_record_all -P madifx_playback_all

I get this error:
> creating alsa driver ...
> madifx_playback_all|madifx_record_all|1024|2|48000|0|0|nomon|swmeter|-|32bit
> jackd: pcm_multi.c:1060: snd_pcm_multi_open: Assertion `!slave_map[sidxs[i]][schannels[i]]' failed.

However, it works when I reduce the amount from 194 to 64 channels per card. I tried to use 128 channels per card, but that fails the same way. See my alsa-info attached, which also includes the .asoundrc content.

I also found this, which might be related: https://ccrma.stanford.edu/mirrors/lalists/lad/2005/06/0202.html

To me, this looks like a bug. What do you think?