Hello, I am working on getting USB MIDI enabled for my device and keep running into this issue: [ 125.702601] kernel BUG at /kernel-source//kernel/locking/rtmutex.c:1048! [ 125.702607] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP [ 125.702764] Call trace: [ 125.702770] rt_spin_lock_slowlock_locked+0x280/0x2b8 [ 125.702774] rt_spin_lock_slowlock+0x5c/0x90 [ 125.702779] rt_spin_lock+0x60/0x70 [ 125.702792] f_midi_transmit+0x90/0x5d8 [usb_f_midi] [ 125.702797] f_midi_complete+0x11c/0x138 [usb_f_midi] [ 125.702809] usb_gadget_giveback_request+0x10/0x18 [ 125.702814] __usbhsg_queue_pop+0x3c/0x58 [ 125.702818] usbhsg_queue_done+0x44/0x60 [ 125.702822] usbhsf_pkt_handler+0x80/0x120 [ 125.702826] usbhs_pkt_start+0x10/0x18 [ 125.702830] usbhsg_queue_push.isra.0+0x44/0x50 [ 125.702834] usbhsg_ep_queue+0x2c/0x40 [ 125.702837] usb_ep_queue+0x24/0x40 [ 125.702843] f_midi_transmit+0x238/0x5d8 [usb_f_midi] [ 125.702848] f_midi_in_tasklet+0xc/0x18 [usb_f_midi] [ 125.702860] tasklet_action_common.isra.2+0xcc/0x1f0 [ 125.702864] tasklet_hi_action+0x20/0x28 [ 125.702869] do_current_softirqs+0x19c/0x248 [ 125.702873] run_ksoftirqd+0x24/0x40 [ 125.702883] smpboot_thread_fn+0x1b0/0x2b8 [ 125.702887] kthread+0x16c/0x170 [ 125.702894] ret_from_fork+0x10/0x1c [ 125.702900] Code: a90363b7 f9000fb4 f90023b9 f9002bbb (d4210000) [ 125.966631] ---[ end trace 0000000000000002 ]--- Seen in the driver code here: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/usb/gadget/function/f_midi.c?h=v4.19.182#n683 We are running a 4.19.182 kernel patched to PREEMPT RT. Has anyone come across this before? I also ask if we've uncovered a bug when using the midi usb gadget with PREEMPT RT. If so, do you have any suggestions for a proper fix? Thanks for your help, ~Jill Donahue
