[PATCH 4.9 076/206] usb: gadget: fix request length error for isoc transfer

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Peter Chen <peter.chen@xxxxxxx>

commit 982555fc26f9d8bcdbd5f9db0378fe0682eb4188 upstream.

For isoc endpoint descriptor, the wMaxPacketSize is not real max packet
size (see Table 9-13. Standard Endpoint Descriptor, USB 2.0 specifcation),
it may contain the number of packet, so the real max packet should be
ep->desc->wMaxPacketSize && 0x7ff.

Cc: Felipe F. Tonello <eu@xxxxxxxxxxxxxxxxx>
Cc: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
Fixes: 16b114a6d797 ("usb: gadget: fix usb_ep_align_maybe
  endianness and new usb_ep_aligna")
Signed-off-by: Peter Chen <peter.chen@xxxxxxx>
Signed-off-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 include/linux/usb/gadget.h |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/include/linux/usb/gadget.h
+++ b/include/linux/usb/gadget.h
@@ -429,7 +429,9 @@ static inline struct usb_gadget *dev_to_
  */
 static inline size_t usb_ep_align(struct usb_ep *ep, size_t len)
 {
-	return round_up(len, (size_t)le16_to_cpu(ep->desc->wMaxPacketSize));
+	int max_packet_size = (size_t)usb_endpoint_maxp(ep->desc) & 0x7ff;
+
+	return round_up(len, max_packet_size);
 }
 
 /**