On Wed, May 13, 2020 at 04:36:20PM -0500, Bin Liu wrote: > When a USB device attached to a hub got disconnected, MUSB controller > generates RXCSR_RX_ERROR interrupt for the 3-strikes-out error. > > Currently the MUSB host driver returns -EPROTO in current URB, then the > USB device driver could immediately resubmit the URB which causes MUSB > generate RXCSR_RX_ERROR interrupt again. This circle causes interrupt > storm then the hub never got a chance to report the USB device detach. > > To fix the interrupt storm, change the URB return code to -ESHUTDOWN for > MUSB_RXCSR_H_ERROR interrupt, so that the USB device driver will not > immediately resubmit the URB. > > Signed-off-by: Bin Liu <b-liu@xxxxxx> Strictly speaking, this is not the right thing to do. It goes against the API described in error-codes.rst. A better approach would be to fix the drivers that immediately resubmit an URB after getting a -EPROTO error. After all, that is the wrong thing to do no matter what sort of host controller the device is attached to. Alan Stern
