+ return 0;
+}
+
+/* set a new max datagram size */
+static void cdc_ncm_set_dgram_size(struct usbnet *dev, int new_size)
+{
+ struct cdc_ncm_ctx *ctx = (struct cdc_ncm_ctx *)dev->data[0];
+ u8 iface_no = ctx->control->cur_altsetting->desc.bInterfaceNumber;
+ __le16 max_datagram_size;
+ u16 mbim_mtu;
+ int err;
+
+ /* set default based on descriptors */
+ ctx->max_datagram_size = clamp_t(u32, new_size,
+ cdc_ncm_min_dgram_size(dev),
+ CDC_NCM_MAX_DATAGRAM_SIZE);
+
+ /* inform the device about the selected Max Datagram Size? */
+ if (!(cdc_ncm_flags(dev) & USB_CDC_NCM_NCAP_MAX_DATAGRAM_SIZE))
+ goto out;
+
+ /* read current mtu value from device */
+ err = usbnet_read_cmd(dev, USB_CDC_GET_MAX_DATAGRAM_SIZE,
+ USB_TYPE_CLASS | USB_DIR_IN | USB_RECIP_INTERFACE,
+ 0, iface_no, &max_datagram_size, 2);
+ if (err < 0) {
+ dev_dbg(&dev->intf->dev, "GET_MAX_DATAGRAM_SIZE failed\n");
+ goto out;
+ }
+
+ if (le16_to_cpu(max_datagram_size) == ctx->max_datagram_size)
+ goto out;
+
+ max_datagram_size = cpu_to_le16(ctx->max_datagram_size);
+ err = usbnet_write_cmd(dev, USB_CDC_SET_MAX_DATAGRAM_SIZE,
+ USB_TYPE_CLASS | USB_DIR_OUT | USB_RECIP_INTERFACE,
+ 0, iface_no, &max_datagram_size, 2);
+ if (err < 0)
+ dev_dbg(&dev->intf->dev, "SET_MAX_DATAGRAM_SIZE failed\n");
+
+out:
+ /* set MTU to max supported by the device if necessary */
+ dev->net->mtu = min_t(int, dev->net->mtu, ctx->max_datagram_size - cdc_ncm_eth_hlen(dev));
+
+ /* do not exceed operater preferred MTU */
+ if (ctx->mbim_extended_desc) {
+ mbim_mtu = le16_to_cpu(ctx->mbim_extended_desc->wMTU);
+ if (mbim_mtu != 0 && mbim_mtu < dev->net->mtu)
+ dev->net->mtu = mbim_mtu;
+ }
+}
+
+static void cdc_ncm_fix_modulus(struct usbnet *dev)
+{
+ struct cdc_ncm_ctx *ctx = (struct cdc_ncm_ctx *)dev->data[0];
+ u32 val;