ChangeSet 1.1337.3.6, 2003/10/23 17:03:25-07:00, [EMAIL PROTECTED]
[PATCH] USB: usbcore, better heuristic for choosing configs
Until now, the Linux-USB core has always chosen the first device
configuration, even when there was a choice. In 2.4 kernels,
device driver probe() routines were allowed to override that
initial policy decisions. But 2.6 kernels can't do that from
probe() routines, causing problems with some CDC-ACM modems
where the first config uses MSFT-proprietary protocols.
This patch switches to a smarter heuristic: Linux now prefers
standard interface classes when there's a choice. So those
CDC-ACM modems don't need a "write bConfigurationValue in sysfs"
step when they are connected; they act just like on 2.4 kernels.
(And sysfs can still be used to handle any problem cases.)
drivers/usb/core/usb.c | 21 +++++++++++++++++----
1 files changed, 17 insertions(+), 4 deletions(-)
diff -Nru a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
--- a/drivers/usb/core/usb.c Mon Dec 29 14:27:37 2003
+++ b/drivers/usb/core/usb.c Mon Dec 29 14:27:37 2003
@@ -991,6 +991,7 @@
int err = -EINVAL;
int i;
int j;
+ int config;
/*
* Set the driver for the usb device to point to the "generic" driver.
@@ -1105,18 +1106,30 @@
/* 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);
+ config, err);
goto fail;
}
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