It's possible that there's no new TRBs prepared when kicking a transfer. This happens when we need to stop and restart a transfer such as in the case of reinitiating a stream or retrying isoc transfer. For streams, sometime host may reject a stream and the device may need to reinitiate that stream by stopping and restarting a transfer. In this case, all the TRBs may have already been prepared. Allow the function __dwc3_gadget_kick_transfer() to go through even though there's no new TRB. Signed-off-by: Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx> --- Changes in v2: - Add a note inline - Revise commit message drivers/usb/dwc3/gadget.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c index 359824c871cd..76c383eecfd3 100644 --- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -1326,8 +1326,13 @@ static int __dwc3_gadget_kick_transfer(struct dwc3_ep *dep) int ret; u32 cmd; + /* + * Note that it's normal to have no new TRBs prepared (i.e. ret == 0). + * This happens when we need to stop and restart a transfer such as in + * the case of reinitiating a stream or retrying an isoc transfer. + */ ret = dwc3_prepare_trbs(dep); - if (ret <= 0) + if (ret < 0) return ret; starting = !(dep->flags & DWC3_EP_TRANSFER_STARTED); base-commit: 9c732b42aa881424b2b918e0f08f1c6f017061d3 -- 2.28.0
