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path: root/drivers/usb/dwc3/gadget.c
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Diffstat (limited to 'drivers/usb/dwc3/gadget.c')
-rw-r--r--drivers/usb/dwc3/gadget.c33
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;