diff --git a/payloads/libpayload/drivers/usb/xhci.c b/payloads/libpayload/drivers/usb/xhci.c
index 87b716c..6a9939c 100644
--- a/payloads/libpayload/drivers/usb/xhci.c
+++ b/payloads/libpayload/drivers/usb/xhci.c
@@ -536,6 +536,7 @@
 		trb->ptr_low = virt_to_phys(cur_start);
 		TRB_SET(TL, trb, cur_length);
 		TRB_SET(TDS, trb, packets);
+		TRB_SET(CH, trb, 1);
 
 		/* Check for first, data stage TRB */
 		if (!trb_count && ep == 1) {
@@ -545,17 +546,19 @@
 			TRB_SET(TT, trb, TRB_NORMAL);
 		}
 
-		/* Check for last TRB */
-		if (!length)
-			TRB_SET(IOC, trb, 1);
-		else
-			TRB_SET(CH, trb, 1);
-
 		xhci_enqueue_trb(tr);
 
 		cur_start += cur_length;
 		++trb_count;
 	}
+
+	trb = tr->cur;
+	xhci_clear_trb(trb, tr->pcs);
+	trb->ptr_low = virt_to_phys(trb);	/* for easier debugging only */
+	TRB_SET(TT, trb, TRB_EVENT_DATA);
+	TRB_SET(IOC, trb, 1);
+
+	xhci_enqueue_trb(tr);
 }
 
 static int
@@ -569,7 +572,7 @@
 	transfer_ring_t *const tr = xhci->dev[dev->address].transfer_rings[1];
 
 	const size_t off = (size_t)data & 0xffff;
-	if ((off + dalen) > ((TRANSFER_RING_SIZE - 3) << 16)) {
+	if ((off + dalen) > ((TRANSFER_RING_SIZE - 4) << 16)) {
 		xhci_debug("Unsupported transfer size\n");
 		return -1;
 	}
@@ -624,11 +627,11 @@
 	xhci->dbreg[dev->address] = 1;
 
 	/* Wait for transfer events */
-	int i, residue = 0;
+	int i, transferred = 0;
 	const int n_stages = 2 + !!dalen;
 	for (i = 0; i < n_stages; ++i) {
 		const int ret = xhci_wait_for_transfer(xhci, dev->address, 1);
-		residue += ret;
+		transferred += ret;
 		if (ret < 0) {
 			if (ret == TIMEOUT) {
 				xhci_debug("Stopping ID %d EP 1\n",
@@ -650,8 +653,8 @@
 	}
 
 	if (dir == IN && data != src)
-		memcpy(src, data, dalen - residue);
-	return dalen - residue;
+		memcpy(src, data, transferred);
+	return transferred;
 }
 
 /* finalize == 1: if data is of packet aligned size, add a zero length packet */
@@ -670,7 +673,7 @@
 	transfer_ring_t *const tr = xhci->dev[slot_id].transfer_rings[ep_id];
 
 	const size_t off = (size_t)data & 0xffff;
-	if ((off + size) > ((TRANSFER_RING_SIZE - 1) << 16)) {
+	if ((off + size) > ((TRANSFER_RING_SIZE - 2) << 16)) {
 		xhci_debug("Unsupported transfer size\n");
 		return -1;
 	}
@@ -718,8 +721,8 @@
 	}
 
 	if (ep->direction == IN && data != src)
-		memcpy(src, data, size - ret);
-	return size - ret;
+		memcpy(src, data, ret);
+	return ret;
 }
 
 static trb_t *
diff --git a/payloads/libpayload/drivers/usb/xhci_events.c b/payloads/libpayload/drivers/usb/xhci_events.c
index b947c7d..dacb5d86 100644
--- a/payloads/libpayload/drivers/usb/xhci_events.c
+++ b/payloads/libpayload/drivers/usb/xhci_events.c
@@ -306,7 +306,7 @@
 	return cc;
 }
 
-/* returns amount of bytes not transferred on success, negative CC on error */
+/* returns amount of bytes transferred on success, negative CC on error */
 int
 xhci_wait_for_transfer(xhci_t *const xhci, const int slot_id, const int ep_id)
 {
diff --git a/payloads/libpayload/drivers/usb/xhci_private.h b/payloads/libpayload/drivers/usb/xhci_private.h
index 9981f07..fbffdb3 100644
--- a/payloads/libpayload/drivers/usb/xhci_private.h
+++ b/payloads/libpayload/drivers/usb/xhci_private.h
@@ -64,7 +64,7 @@
 enum {
 	TRB_NORMAL = 1,
 	TRB_SETUP_STAGE = 2, TRB_DATA_STAGE = 3, TRB_STATUS_STAGE = 4,
-	TRB_LINK = 6,
+	TRB_LINK = 6, TRB_EVENT_DATA = 7,
 	TRB_CMD_ENABLE_SLOT = 9, TRB_CMD_DISABLE_SLOT = 10, TRB_CMD_ADDRESS_DEV = 11,
 	TRB_CMD_CONFIGURE_EP = 12, TRB_CMD_EVAL_CTX = 13, TRB_CMD_RESET_EP = 14,
 	TRB_CMD_STOP_EP = 15, TRB_CMD_SET_TR_DQ = 16, TRB_CMD_NOOP = 23,
@@ -149,6 +149,7 @@
 	u8 adv;
 } event_ring_t;
 
+/* Never raise this above 256 to prevent transfer event length overflow! */
 #define TRANSFER_RING_SIZE 32
 typedef struct {
 	trb_t *ring;