[PATCH 2.6.31] rndis_host: extra interrupt for problematic devices

[Mark Ellis]

From: Mark Ellis <m...@mpellis.org.uk>

Certain devices, particularly those with Samsung processors, show
difficulties connecting via RNDIS, specifically resulting in -110
errors in driver initialisation.

This patch, resulting from comparisons with an obsolete user mode
driver, overcomes this in all tested cases.

Signed-off-by: Mark Ellis <m...@mpellis.org.uk>
---
diff -Nurp linux-source-2.6.31.orig/drivers/net/usb/rndis_host.c 
linux-source-2.6.31/drivers/net/usb/rndis_host.c
--- linux-source-2.6.31.orig/drivers/net/usb/rndis_host.c       2009-09-09 
23:13:59.000000000 +0100
+++ linux-source-2.6.31/drivers/net/usb/rndis_host.c    2010-02-16 
19:03:12.497106220 +0000
@@ -64,6 +64,25 @@ void rndis_status(struct usbnet *dev, st
 }
 EXPORT_SYMBOL_GPL(rndis_status);
 
+/* Function copied from keyspan_remote.c */
+static struct usb_endpoint_descriptor *rndis_get_in_endpoint(struct 
usb_host_interface *iface)
+{
+
+        struct usb_endpoint_descriptor *endpoint;
+        int i;
+
+        for (i = 0; i < iface->desc.bNumEndpoints; ++i) {
+                endpoint = &iface->endpoint[i].desc;
+
+                if (usb_endpoint_is_int_in(endpoint)) {
+                        /* we found our interrupt in endpoint */
+                        return endpoint;
+                }
+        }
+
+        return NULL;
+}
+
 /*
  * RPC done RNDIS-style.  Caller guarantees:
  * - message is properly byteswapped
@@ -77,11 +96,14 @@ EXPORT_SYMBOL_GPL(rndis_status);
 int rndis_command(struct usbnet *dev, struct rndis_msg_hdr *buf, int buflen)
 {
        struct cdc_state        *info = (void *) &dev->data;
+       struct usb_endpoint_descriptor *endpoint;
        int                     master_ifnum;
        int                     retval;
        unsigned                count;
        __le32                  rsp;
        u32                     xid = 0, msg_len, request_id;
+       char                    *int_buf = NULL;
+       int                     maxp, pipe, partial;
 
        /* REVISIT when this gets called from contexts other than probe() or
         * disconnect(): either serialize, or dispatch responses on xid
@@ -110,6 +132,38 @@ int rndis_command(struct usbnet *dev, st
        // we time out and cancel our "get response" requests...
        // so, this is fragile.  Probably need to poll for status.
 
+        /* Certain rndis devices, particularly with Samsung processors,
+        * are problematic. An interrupt message appears to fix this.
+        */
+
+       int_buf = kmalloc(128, GFP_KERNEL);
+       if (!int_buf)
+               return -ENOMEM;
+
+        endpoint = rndis_get_in_endpoint(info->control->cur_altsetting);
+        pipe = usb_rcvintpipe(dev->udev, endpoint->bEndpointAddress);
+        maxp = usb_maxpacket(dev->udev, pipe, usb_pipeout(pipe));
+
+        retval = usb_interrupt_msg(dev->udev,
+                                   pipe,
+                                   int_buf,
+                                   (maxp > 8 ? 8 : maxp),
+                                   &partial,
+                                   RNDIS_CONTROL_TIMEOUT_MS);
+       kfree(int_buf);
+
+        dev_dbg(&info->control->dev,
+                "pipe: %d, maxp: %d, partial: %d, retval: %d\n",
+                pipe,
+                maxp,
+                partial,
+                retval);
+
+        /* I /think/ usb_interrupt_msg blocks and returns < 0 for error */
+        if (unlikely(retval < 0))
+                return retval;
+
+
        /* ignore status endpoint, just poll the control channel;
         * the request probably completed immediately
         */

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