usb.c patch -> successfuly read usb descriptors on some USB device

Hi,

Sometimes USB subsystem cannot get USB descriptor.

Jan 15 10:44:21 selma kernel: hub.c: USB new device connect on bus1/1, assign
ed device number 25
Jan 15 10:44:21 selma kernel: usb.c: couldn't get all of config descriptors
Jan 15 10:44:21 selma kernel: usb.c: unable to get device 25 configuration (e

rror=-110)

Here is patch how to fix it for 2.4.17. It works for 2.4.16 as well. It necassary to read descriptor at once, not first 8 byte first.

It works well now for NSM USB Bluetooth dongle.

br, Dmitri

----------------------------- CUT HERE ---------------------------------------------------------

@@ -2041,7 +2041,7 @@

		return -ENOMEM;
	}

- buffer = kmalloc(8, GFP_KERNEL);

+	buffer = kmalloc(255, GFP_KERNEL);
	if (!buffer) {
		err("unable to allocate memory for configuration descriptors");
		return -ENOMEM;
@@ -2049,9 +2049,9 @@
	desc = (struct usb_config_descriptor *)buffer;

	for (cfgno = 0; cfgno < dev->descriptor.bNumConfigurations; cfgno++) {
-		/* We grab the first 8 bytes so we know how long the whole */
+		/* We grab the first 255 bytes so we know how long the whole */
		/*  configuration is */
-		result = usb_get_descriptor(dev, USB_DT_CONFIG, cfgno, buffer, 8);
+		result = usb_get_descriptor(dev, USB_DT_CONFIG, cfgno, buffer, 255);
		if (result < 8) {
			if (result < 0)
				err("unable to get descriptor");
@@ -2072,19 +2072,24 @@
			goto err;
		}

- /* Now that we know the length, get the whole thing */
- result = usb_get_descriptor(dev, USB_DT_CONFIG, cfgno, bigbuffer, length);
- if (result < 0) {
- err("couldn't get all of config descriptors");
- kfree(bigbuffer);
- goto err;
- }
+ if (length > 255) {
+ /* Now that we know the length, get the whole thing */
+ result = usb_get_descriptor(dev, USB_DT_CONFIG, cfgno, bigbuffer, length);
+ if (result < 0) {
+ err("couldn't get all of config descriptors");
+ kfree(bigbuffer);
+ goto err;
+ }

- if (result < length) {
- err("config descriptor too short (expected %i, got %i)", length, result);
- result = -EINVAL;
- kfree(bigbuffer);
- goto err;
+ if (result < length) {
+ err("config descriptor too short (expected %i, got %i)", length, result);
+ result = -EINVAL;
+ kfree(bigbuffer);
+ goto err;
+ }
+ }
+ else {

+			memcpy(bigbuffer, buffer, length);
		}

		dev->rawdescriptors[cfgno] = bigbuffer;

-------------- CUT HERE ----------------------------------------------------------------------------

Dmitri Kassatkine
Nokia Research Center / Helsinki
Mobile: +358 50 4836365
E-Mail: [email protected]

Then this device does not match the USB spec.

Has this device gone through the USB certification process? There are a _lot_ of USB bluetooth devices out there that violate the USB spec, and have not been certified.

thanks,

greg k-h