usb: gadget: udc: renesas_usb3: fix Pn_RAMMAP.Pn_MPKT value

According to the datasheet of R-Car Gen3, the Pn_RAMMAP.Pn_MPKT should
be set to one of 8, 16, 32, 64, 512 and 1024. Otherwise, when a gadget
driver uses an interrupt endpoint, unexpected behavior happens. So,
this patch fixes it.

Fixes: 746bfe6 ("usb: gadget: renesas_usb3: add support for Renesas USB3.0 peripheral controller")
Cc: <stable@vger.kernel.org> # v4.5+
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/gadget/udc/renesas_usb3.c

@@ -2054,7 +2054,16 @@ static u32 usb3_calc_ramarea(int ram_size)
 static u32 usb3_calc_rammap_val(struct renesas_usb3_ep *usb3_ep,
 				const struct usb_endpoint_descriptor *desc)
 {
-	return usb3_ep->rammap_val | PN_RAMMAP_MPKT(usb_endpoint_maxp(desc));
+	int i;
+	const u32 max_packet_array[] = {8, 16, 32, 64, 512};
+	u32 mpkt = PN_RAMMAP_MPKT(1024);
+
+	for (i = 0; i < ARRAY_SIZE(max_packet_array); i++) {
+		if (usb_endpoint_maxp(desc) <= max_packet_array[i])
+			mpkt = PN_RAMMAP_MPKT(max_packet_array[i]);
+	}
+
+	return usb3_ep->rammap_val | mpkt;
 }
 
 static int usb3_enable_pipe_n(struct renesas_usb3_ep *usb3_ep,