usb: chipidea: udc: using MultO at TD as real mult value for ISO-TX

We have met a bug that the high bandwidth ISO-TX transfer has failed
at the last packet if it is less than 1024, the TD status shows it
is "Transaction Error".

The root cause of this problem is: the mult value at qh is not correct
for current TD's transfer length. We use TD list to queue un-transfer
TDs, and change mult for new adding TDs. If new adding TDs transfer length
less than 1024, but the queued un-transfer TDs transfer length is larger
than 1024, the transfer error will occur, and vice versa.
Usually, this problem occurs at the last packet, and the first packet for
new frame.

We fixed this problem by setting Mult at QH as the largest value (3), and
set MultO (Multiplier Override) at TD according to every transfer length.
It can cover both hardware version less than 2.3 (the real mult is MultO
if it is not 0) and 2.3+ (the real mult is min(qh.mult, td.multo)).

Since the MultO bits are only existed at TX TD, we keep the ISO-RX behavior
unchanged.

For stable tree: 3.11+.

Cc: stable <stable@vger.kernel.org>
Cc: Michael Grzeschik <m.grzeschik@pengutronix.de>
Reported-by: Matthieu Vanin <b47495@freescale.com>
Tested-by: Matthieu Vanin <b47495@freescale.com>
Signed-off-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/chipidea/udc.c

@@ -393,6 +393,14 @@ static int add_td_to_list(struct ci_hw_ep *hwep, struct ci_hw_req *hwreq,
 	node->ptr->token = cpu_to_le32(length << __ffs(TD_TOTAL_BYTES));
 	node->ptr->token &= cpu_to_le32(TD_TOTAL_BYTES);
 	node->ptr->token |= cpu_to_le32(TD_STATUS_ACTIVE);
+	if (hwep->type == USB_ENDPOINT_XFER_ISOC && hwep->dir == TX) {
+		u32 mul = hwreq->req.length / hwep->ep.maxpacket;
+
+		if (hwreq->req.length == 0
+				|| hwreq->req.length % hwep->ep.maxpacket)
+			mul++;
+		node->ptr->token |= mul << __ffs(TD_MULTO);
+	}
 
 	temp = (u32) (hwreq->req.dma + hwreq->req.actual);
 	if (length) {
@@ -515,10 +523,11 @@ static int _hardware_enqueue(struct ci_hw_ep *hwep, struct ci_hw_req *hwreq)
 	hwep->qh.ptr->td.token &=
 		cpu_to_le32(~(TD_STATUS_HALTED|TD_STATUS_ACTIVE));
 
-	if (hwep->type == USB_ENDPOINT_XFER_ISOC) {
+	if (hwep->type == USB_ENDPOINT_XFER_ISOC && hwep->dir == RX) {
 		u32 mul = hwreq->req.length / hwep->ep.maxpacket;
 
-		if (hwreq->req.length % hwep->ep.maxpacket)
+		if (hwreq->req.length == 0
+				|| hwreq->req.length % hwep->ep.maxpacket)
 			mul++;
 		hwep->qh.ptr->cap |= mul << __ffs(QH_MULT);
 	}
@@ -1173,6 +1182,12 @@ static int ep_enable(struct usb_ep *ep,
 	if (hwep->num)
 		cap |= QH_ZLT;
 	cap |= (hwep->ep.maxpacket << __ffs(QH_MAX_PKT)) & QH_MAX_PKT;
+	/*
+	 * For ISO-TX, we set mult at QH as the largest value, and use
+	 * MultO at TD as real mult value.
+	 */
+	if (hwep->type == USB_ENDPOINT_XFER_ISOC && hwep->dir == TX)
+		cap |= 3 << __ffs(QH_MULT);
 
 	hwep->qh.ptr->cap = cpu_to_le32(cap);