[PATCH v2] net: cdc_ether: allow combined control and data interface

["Bjørn Mork" <bjorn-yOkvZcmFvRU@public.gmane.org>]

Some Icera based Huawei modems handled by this driver are not
completely CDC ECM compliant, using the same USB interface for both
control and data. The CDC functional descriptors include a Union
naming this interface as both master and slave, so it is supportable
by relaxing the descriptor parsing in case these interfaces are
identical.

This has been tested on a Huawei K3806 and verified to add support
for that device.

Reported-and-tested-by: Enrico Mioso <mrkiko.rs-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Signed-off-by: Bjørn Mork <bjorn-yOkvZcmFvRU@public.gmane.org>
---
v2: Simplified unbind logic.  Thanks to Oliver Neukum


 drivers/net/usb/cdc_ether.c |   22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/drivers/net/usb/cdc_ether.c b/drivers/net/usb/cdc_ether.c
index 04ee044..4393f14 100644
--- a/drivers/net/usb/cdc_ether.c
+++ b/drivers/net/usb/cdc_ether.c
@@ -215,6 +215,10 @@ int usbnet_generic_cdc_bind(struct usbnet *dev, struct usb_interface *intf)
 					goto bad_desc;
 			}
 
+			/* some devices merge these - skip class check */
+			if (info->control == info->data)
+				goto next_desc;
+
 			/* a data interface altsetting does the real i/o */
 			d = &info->data->cur_altsetting->desc;
 			if (d->bInterfaceClass != USB_CLASS_CDC_DATA) {
@@ -304,19 +308,23 @@ next_desc:
 	/* claim data interface and set it up ... with side effects.
 	 * network traffic can't flow until an altsetting is enabled.
 	 */
-	status = usb_driver_claim_interface(driver, info->data, dev);
-	if (status < 0)
-		return status;
+	if (info->data != info->control) {
+		status = usb_driver_claim_interface(driver, info->data, dev);
+		if (status < 0)
+			return status;
+	}
 	status = usbnet_get_endpoints(dev, info->data);
 	if (status < 0) {
 		/* ensure immediate exit from usbnet_disconnect */
 		usb_set_intfdata(info->data, NULL);
-		usb_driver_release_interface(driver, info->data);
+		if (info->data != info->control)
+			usb_driver_release_interface(driver, info->data);
 		return status;
 	}
 
 	/* status endpoint: optional for CDC Ethernet, not RNDIS (or ACM) */
-	dev->status = NULL;
+	if (info->data != info->control)
+		dev->status = NULL;
 	if (info->control->cur_altsetting->desc.bNumEndpoints == 1) {
 		struct usb_endpoint_descriptor	*desc;
 
@@ -349,6 +357,10 @@ void usbnet_cdc_unbind(struct usbnet *dev, struct usb_interface *intf)
 	struct cdc_state		*info = (void *) &dev->data;
 	struct usb_driver		*driver = driver_of(intf);
 
+	/* combined interface - nothing  to do */
+	if (info->data == info->control)
+		return;
+
 	/* disconnect master --> disconnect slave */
 	if (intf == info->control && info->data) {
 		/* ensure immediate exit from usbnet_disconnect */
-- 
1.7.10.4

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