Changing performances with rotary encoder crashes in USB Gadget Mode

[probonopd]

On a Raspberry Pi Zero 2 with a 0.96" OLED via i2c and no i2s DAC:

• Installed MiniDexed_2023-12-05-e5b2656
• Enabled USB Gadget Mode
• Set sound output to HDMI
• Attached Pi to host computer (in this case, a Raspberry Pi 5) via the original Raspberry Pi USB Keyboard and Hub
• Using REAPER, played a MIDI song out to the MiniDexed USB Gadget port. Works beautifully
• Using the rotary encoder, loaded performance "Concert D" while the MIDI was playing. No issues so far
• Same for "The Grand", "Rock Piano", "Cinematic", "Piano + Pad", "SimpleM.CP-70", "Phil's CP-70", "mDX-Ballade". No issues so far
• When I select "Legend'83" it crashes and I hear a looping sound.

I can reproduce this. It is the 9th time I try to load a performance that I get the crash.

When the crash happens, dmesg on the host PC says

sound midiC0D0: rawmidi drain error (avail = 3353, buffer_size = 4096)

(Note: This does not happen when I don't use USB Gadget Mode but attach a MIDI controller instead. Then I can load performances more often than 8 times both with the rotary encoder and via MIDI without the crash.)

Additional information:

• The freeze only happens when the device is connected to a host PC in USB gadget mode
• The freeze also happens when I am not playing a MIDI at the same time
• The freeze does not happen when USB gadget mode is disabled (even if powered via the same USB port at the same host PC)
• The freeze does not always happen exactly at the 9th performance, it seems to be more like a ~1/10th probability of a freeze on every performance change