diff options
Diffstat (limited to 'drivers/usb/dwc3')
| -rw-r--r-- | drivers/usb/dwc3/gadget.c | 33 |
1 files changed, 32 insertions, 1 deletions
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c index 6b299c7b7656..f064f1549333 100644 --- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -896,9 +896,40 @@ static void __dwc3_prepare_one_trb(struct dwc3_ep *dep, struct dwc3_trb *trb, if (!node) { trb->ctrl = DWC3_TRBCTL_ISOCHRONOUS_FIRST; + /* + * USB Specification 2.0 Section 5.9.2 states that: "If + * there is only a single transaction in the microframe, + * only a DATA0 data packet PID is used. If there are + * two transactions per microframe, DATA1 is used for + * the first transaction data packet and DATA0 is used + * for the second transaction data packet. If there are + * three transactions per microframe, DATA2 is used for + * the first transaction data packet, DATA1 is used for + * the second, and DATA0 is used for the third." + * + * IOW, we should satisfy the following cases: + * + * 1) length <= maxpacket + * - DATA0 + * + * 2) maxpacket < length <= (2 * maxpacket) + * - DATA1, DATA0 + * + * 3) (2 * maxpacket) < length <= (3 * maxpacket) + * - DATA2, DATA1, DATA0 + */ if (speed == USB_SPEED_HIGH) { struct usb_ep *ep = &dep->endpoint; - trb->size |= DWC3_TRB_SIZE_PCM1(ep->mult - 1); + unsigned int mult = ep->mult - 1; + unsigned int maxp = usb_endpoint_maxp(ep->desc); + + if (length <= (2 * maxp)) + mult--; + + if (length <= maxp) + mult--; + + trb->size |= DWC3_TRB_SIZE_PCM1(mult); } } else { trb->ctrl = DWC3_TRBCTL_ISOCHRONOUS; |