[media] rtl28xxu: dynamic USB ID support

DVB USB core refuses to	load driver when current USB ID
does not match IDs on driver table. Due to that dynamic
IDs does not work. Replace reference design ID by dynamic
ID in .probe() in order to get it working.
Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/dvb/dvb-usb/rtl28xxu.c

@@ -909,6 +909,8 @@ static int rtl28xxu_probe(struct usb_interface *intf,
 	int ret, i;
 	int properties_count = ARRAY_SIZE(rtl28xxu_properties);
 	struct dvb_usb_device *d;
+	struct usb_device *udev;
+	bool found;
 
 	deb_info("%s: interface=%d\n", __func__,
 		intf->cur_altsetting->desc.bInterfaceNumber);
@@ -916,6 +918,29 @@ static int rtl28xxu_probe(struct usb_interface *intf,
 	if (intf->cur_altsetting->desc.bInterfaceNumber != 0)
 		return 0;
 
+	/* Dynamic USB ID support. Replaces first device ID with current one .*/
+	udev = interface_to_usbdev(intf);
+
+	for (i = 0, found = false; i < ARRAY_SIZE(rtl28xxu_table) - 1; i++) {
+		if (rtl28xxu_table[i].idVendor ==
+				le16_to_cpu(udev->descriptor.idVendor) &&
+				rtl28xxu_table[i].idProduct ==
+				le16_to_cpu(udev->descriptor.idProduct)) {
+			found = true;
+			break;
+		}
+	}
+
+	if (!found) {
+		deb_info("%s: using dynamic ID %04x:%04x\n", __func__,
+				le16_to_cpu(udev->descriptor.idVendor),
+				le16_to_cpu(udev->descriptor.idProduct));
+		rtl28xxu_properties[0].devices[0].warm_ids[0]->idVendor =
+				le16_to_cpu(udev->descriptor.idVendor);
+		rtl28xxu_properties[0].devices[0].warm_ids[0]->idProduct =
+				le16_to_cpu(udev->descriptor.idProduct);
+	}
+
 	for (i = 0; i < properties_count; i++) {
 		ret = dvb_usb_device_init(intf, &rtl28xxu_properties[i],
 				THIS_MODULE, &d, adapter_nr);