RE: [PATCH 1/3] net: cdc_ncm: add get/set ethernet address functions

[Charles.Hyde]

<snipped> 
> static int cdc_ncm_init(struct usbnet *dev) {
>       struct cdc_ncm_ctx *ctx = (struct cdc_ncm_ctx *)dev->data[0];
>       u8 iface_no = ctx->control->cur_altsetting->desc.bInterfaceNumber;
>       int err;
> 
>       err = usbnet_read_cmd(dev, USB_CDC_GET_NTB_PARAMETERS,
>                             USB_TYPE_CLASS | USB_DIR_IN
>                             |USB_RECIP_INTERFACE,
>                             0, iface_no, &ctx->ncm_parm,
>                             sizeof(ctx->ncm_parm));
> ,,
> 
> You'll obviously have to replace USB_CDC_GET_NTB_PARAMETERS with
> USB_CDC_GET_NET_ADDRESS, &ctx->ncm_parm with buf, and
> sizeof(ctx->ncm_parm) with ETH_ALEN.
> 
> 
> Bjørn

Not everything is obvious to those who do not live and breathe USB.  This has 
been an experience.

Is this snippet what you have in mind?  Will iface_no be correct?  If not, then 
what do you suggest?

/* Provide method to push MAC address to the USB device's ethernet controller.
 * If the device does not support CDC_SET_ADDRESS, there is no harm and we
 * proceed as before.
 */
static int cdc_ncm_set_ethernet_address(struct usbnet *dev,
                                        struct sockaddr *addr)
{
        int ret;
        struct cdc_ncm_ctx *ctx = (struct cdc_ncm_ctx *)dev->data[0];
        u8 iface_no = ctx->control->cur_altsetting->desc.bInterfaceNumber;

        ret = usbnet_write_cmd(dev, USB_CDC_SET_NET_ADDRESS,
                               USB_DIR_OUT | USB_TYPE_CLASS
                               | USB_RECIP_INTERFACE, 0, iface_no,
                               addr->sa_data, ETH_ALEN);
        if (ret == ETH_ALEN)
                ret = 0;        /* success */
        else if (ret < 0)
                dev_dbg(&dev->udev->dev, "bad MAC address put, %d\n", ret);

        return ret;
}