Subject: Re: [PATCH] CDC_NCM adding support IFF_NOARP for buggy device

From: Oliver Neukum <[email-masked]>
Date: Thu, 10 Jan 2013 15:10:49 +0100

On Thursday 10 January 2013 21:59:28 Wei Shuai wrote:

Hi,

I am afraid this is done in an unclean manner.

> diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c
> index 71b6e92..9903f79 100644
> --- a/drivers/net/usb/cdc_ncm.c
> +++ b/drivers/net/usb/cdc_ncm.c
> @@ -545,6 +545,7 @@ EXPORT_SYMBOL_GPL(cdc_ncm_unbind);
>  static int cdc_ncm_bind(struct usbnet *dev, struct usb_interface *intf)
>  {
>  	int ret;
> +	struct usb_device *udev = interface_to_usbdev(intf);
>  
>  	/* The MBIM spec defines a NCM compatible default altsetting,
>  	 * which we may have matched:
> @@ -572,6 +573,10 @@ static int cdc_ncm_bind(struct usbnet *dev, struct usb_interface *intf)
>  	    cdc_ncm_comm_intf_is_mbim(intf->cur_altsetting))
>  		return -ENODEV;
>  #endif
> +	/*  this buggy device cannot do ARP */
> +	if( (le16_to_cpu(udev->descriptor.idVendor) == 0xAAAA) ) {
> +		dev->net->flags |= IFF_NOARP;

So either you do a check here ...

> +	}
>  
>  	/* NCM data altsetting is always 1 */
>  	ret = cdc_ncm_bind_common(dev, intf, 1);
> @@ -1186,6 +1191,16 @@ static const struct usb_device_id cdc_devs[] = {
>  	  .driver_info = (unsigned long) &wwan_info,
>  	},
>  
> +	/* buggy device cannot send ARP */
> +	{ .match_flags = USB_DEVICE_ID_MATCH_INT_INFO
> +		| USB_DEVICE_ID_MATCH_VENDOR,
> +	  .idVendor = 0xAAAA,
> +	  .bInterfaceClass = USB_CLASS_COMM,
> +	  .bInterfaceSubClass = USB_CDC_SUBCLASS_NCM,
> +	  .bInterfaceProtocol = USB_CDC_PROTO_NONE,
> +	  .driver_info = (unsigned long) &wwan_info,

... or you define a matching id here and give it a flag in driver_info

But not both.

	Regards
		Oliver