On Thu, Jan 24, 2019 at 10:49:30AM -0500, Alan Stern wrote: > On Thu, 24 Jan 2019, Bin Liu wrote: > > > > 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. > > > > 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_BH to 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.
