Re: ACM USB modem on Kernel 2.6.0-test

[David Brownell <david-b@pacbell.net>]

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David Brownell wrote:
> 
> Hmm ... maybe usbcore would be better off with a less
> naive algorithm for choosing defaults.  Like, preferring
> configurations without proprietary device protocols.
> That'd solve every cdc-acm case, and likely others.

In fact, here's a patch with that very change.  Does
it make current 2.6.0-test kernels work "out of the box"
again with your USB modems?

- Dave




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--- 1.143/drivers/usb/core/usb.c	Thu Sep 25 03:59:51 2003
+++ edited/drivers/usb/core/usb.c	Fri Oct 17 12:18:16 2003
@@ -991,6 +997,7 @@
 	int err = -EINVAL;
 	int i;
 	int j;
+	int config;
 
 	/*
 	 * Set the driver for the usb device to point to the "generic" driver.
@@ -1105,15 +1112,27 @@
 
 	/* choose and set the configuration. that registers the interfaces
 	 * with the driver core, and lets usb device drivers bind to them.
+	 * NOTE:  should interact with hub power budgeting.
 	 */
+	config = dev->config[0].desc.bConfigurationValue;
 	if (dev->descriptor.bNumConfigurations != 1) {
+		for (i = 0; i < dev->descriptor.bNumConfigurations; i++) {
+			/* heuristic:  Linux is more likely to have class
+			 * drivers, so avoid vendor-specific interfaces.
+			 */
+			if (dev->config[i].interface[0]->altsetting
+						->desc.bInterfaceClass
+					== USB_CLASS_VENDOR_SPEC)
+				continue;
+			config = dev->config[i].desc.bConfigurationValue;
+			break;
+		}
 		dev_info(&dev->dev,
 			"configuration #%d chosen from %d choices\n",
-			dev->config[0].desc.bConfigurationValue,
+			config,
 			dev->descriptor.bNumConfigurations);
 	}
-	err = usb_set_configuration(dev,
-			dev->config[0].desc.bConfigurationValue);
+	err = usb_set_configuration(dev, config);
 	if (err) {
 		dev_err(&dev->dev, "can't set config #%d, error %d\n",
 			dev->config[0].desc.bConfigurationValue, err);