MUSB interrupt storm on device removal
Quoted 6 lines · Alan Stern
Quoted 4 lines · Bin Liu
Quoted 3 lines
Perhaps it has something to do with the timing of the completion interrupts. I don't know anything about how musb works, though. Some low-level timing information would be good to see.
Quoted 8 lines
Quoted 4 lines
The musb controller driver itself doesn't have a isr BH, so when an ep interrupt happened, the isr directly processes the urb and called giveback. I tried to add
HCD_BHto the musb hcd .flag, the issue still happens.I was thinking that maybe some controllers delay some types of completion interrupt until a frame boundary, while other controllers raise all completion interrupts immediately.
It is interesting that A20 which uses musb controller too doesn't show the issue. We really have to compare the runtime on A20 and BeagleboneBlack to understand the problem.
Regards,
-Bin.