On 20.5.2021 23.30, Thinh Nguyen wrote: > +Mathias > ... > Hm... looks like we have a couple of issues in the uas storage class > driver and the xhci driver. > > We may need to fix that in the uas storage driver because it doesn't > seem to handle it. (check uas_data_cmplt() in uas.c). > > As for the xhci driver, there maybe a case where the stream URB never > gets to complete because the transaction err_count is not properly > updated. The err_count for transaction error is stored in ep_ring, but > the xhci driver may not be able to lookup the correct ep_ring based on > TRB address for streams. There are cases for streams where the event > TRBs have their TRB pointer field cleared to '0' (xhci spec section > 4.12.2). If the xhci driver doesn't see ep_ring for transaction error, > it automatically does a soft-retry. This is seen from one of our > testings that the driver was repeatedly doing soft-retry until the class > driver timed out. > > Hi Mathias, maybe you have some comment on this? Thanks. This is true, if TRB pointer is 0 then there is no retry limit for soft retry. We should add one and prevent a loop. after e few soft resets we can end with a hard reset to clear the host side endpoint halt. We don't know the URB that was being tansferred during the error, and can't give it back with a proper error code. In that sense we still end up waiting for a timeout and someone to cancel the urb. -Mathias
