The Set TR Deq command instructs the hardware to skip Transfer Descriptors (TDs) from A to B. Once the hardware processes the Set TR Deq command, it returns a completion event indicating either success or an error. In the event of success, TDs A to B are released, the dequeue pointer is updated, and if there are still cancelled TDs, a new Set TR Deq command is issued. Conversely, if an error occurs, a warning is logged, and TDs A to B are released. This can lead to a mismatch between the driver and hardware, eventually resulting in an critical error. When feasible, attempt to resolve errors. Otherwise, retain unresolved errors as they are and improve the warning message. xHCI driver issues Set TR Deq commands in 4 places: xhci_handle_cmd_stop_ep() After a successful Stop Endpoint completion event is received. xhci_handle_cmd_set_deq() After receiving a Set TR Deq completion event and there are new cancelled TDs. xhci_handle_cmd_reset_ep() After a Endpoint reset completion, Endpoint state is Stopped. xhci_urb_dequeue() If clearing Endpoints Transaction Translator, Endpoint state is Stopped. Niklas Neronin (4): usb: xhci: handle Set TR Deq TRB Error usb: xhci: handle Set TR Deq Slot Not Enabled Error usb: xhci: handle Set TR Deq Context State Error due to Slot state usb: xhci: handle Set TR Deq Context State Error due to Endpoint state drivers/usb/host/xhci-ring.c | 68 ++++++++++++++++++++++++++++-------- 1 file changed, 54 insertions(+), 14 deletions(-) -- 2.50.1
