To avoid a potential underrun of an currently drained transfer we add a check for that scenario in the dwc3_gadget_endpoint_trbs_complete function. In the case of an empty trb ring, we call the stop_transfer cmd and avoid the underrun to occur. Signed-off-by: Michael Grzeschik <m.grzeschik@xxxxxxxxxxxxxx> --- Changes in v2: - dropped patch "usb: dwc3: gadget: reclaim the whole started list when request was missed" - fixed patch "usb: dwc3: gadget: check drained isoc ep" - dropped patch "usb: dwc3: gadget: check the whole started queue for missed requests in complete" - Link to v1: https://lore.kernel.org/r/20240307-dwc3-gadget-complete-irq-v1-0-4fe9ac0ba2b7@xxxxxxxxxxxxxx --- drivers/usb/dwc3/gadget.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c index 4df2661f66751..3e9c67799259a 100644 --- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -3582,13 +3582,26 @@ static bool dwc3_gadget_endpoint_trbs_complete(struct dwc3_ep *dep, if (!dep->endpoint.desc) return no_started_trb; - if (usb_endpoint_xfer_isoc(dep->endpoint.desc) && - list_empty(&dep->started_list) && - (list_empty(&dep->pending_list) || status == -EXDEV)) - dwc3_stop_active_transfer(dep, true, true); - else if (dwc3_gadget_ep_should_continue(dep)) + if (usb_endpoint_xfer_isoc(dep->endpoint.desc)) { + /* It is possible that the interrupt thread was delayed + * by scheduling in the system, and therefor the HW has + * already run dry. In that case the last trb in the + * queue is already handled by the hw. By checking the + * HWO bit we know to restart the whole transfer. The + * condition to appear is more likely if not every req + * has the IOC bit set and therefor does not trigger the + * interrupt thread frequently. + */ + struct dwc3_trb *trb = dwc3_ep_prev_trb(dep, dep->trb_enqueue); + unsigned int transfer_in_flight = trb->ctrl & DWC3_TRB_CTRL_HWO; + + if ((list_empty(&dep->started_list) || !transfer_in_flight) && + (list_empty(&dep->pending_list) || status == -EXDEV)) + dwc3_stop_active_transfer(dep, true, true); + } else if (dwc3_gadget_ep_should_continue(dep)) { if (__dwc3_gadget_kick_transfer(dep) == 0) no_started_trb = false; + } out: /* --- base-commit: 5bab5dc780c9ed0c69fc2f828015532acf4a7848 change-id: 20240307-dwc3-gadget-complete-irq-1a8ffa347fd1 Best regards, -- Michael Grzeschik <m.grzeschik@xxxxxxxxxxxxxx>
