Yesterday I acquired Rasp Pi 3, installed Raspbian, and started my long lusted midi sequencer project. At the end of the day, I need to connect 11 USB MIDI devices using powered MIDI hubs. Note that I have done this on regular PC using Ubuntu. No problems there. When I try to replicate my setup from Ubuntu to Raspbian, it turns out that I can not connect more than 7 external devices (total of eight including the stock 'Midi Through Port-0'). Each new MIDI USB device is recognized, but the dmesg output is:
[ 681.974078] snd-usb-audio 1-1.4.3:1.0: cannot find the slot for index -1 (range 0-7), error: -19
[ 681.974103] usb 1-1.4.3: cannot create card instance 7
[ 681.974480] snd-usb-audio 1-1.4.3:1.1: cannot find the slot for index -1 (range 0-7), error: -19
[ 681.974502] usb 1-1.4.3: cannot create card instance 7
no matter the 9-th device I connect. Any useful info regarding this issue will be highly appreciated.
Thanks in advance