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>
---
drivers/usb/dwc3/gadget.c | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index b9fce7b1dcdec..f22b68a0b2dac 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -3568,8 +3568,23 @@ static bool dwc3_gadget_endpoint_trbs_complete(struct dwc3_ep *dep,
{
struct dwc3 *dwc = dep->dwc;
bool no_started_trb = true;
+ unsigned int transfer_in_flight = 0;
+
+ /* 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.
+ */
+ if (dep->number && usb_endpoint_xfer_isoc(dep->endpoint.desc)) {
+ struct dwc3_trb *trb = dwc3_ep_prev_trb(dep, dep->trb_enqueue);
+
+ transfer_in_flight = trb->ctrl & DWC3_TRB_CTRL_HWO;
+ }
- if (status == -EXDEV)
+ if (status == -EXDEV || !transfer_in_flight)
dwc3_stop_active_transfer(dep, true, true);
dwc3_gadget_ep_cleanup_completed_requests(dep, event, status);
--
2.39.2
