USB: unconfigure devices which have config 0
Some USB devices do have a configuration 0, in contravention of the
USB spec. Normally 0 is supposed to indicate that a device is
unconfigured.
While we can't change what the device is doing, we can change usbcore.
This patch (as852) allows usb_set_configuration() to accept a config
value of -1 as indicating that the device should be unconfigured. The
request actually sent to the device will still contain 0 as the value.
But even if the device does have a configuration 0, dev->actconfig
will be set to NULL and dev->state will be set to USB_STATE_ADDRESS.
Without some sort of special-case handling like this, there is no way
to unconfigure these non-compliant devices.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/core/generic.c b/drivers/usb/core/generic.c
index b531a4f..9bbcb20 100644
--- a/drivers/usb/core/generic.c
+++ b/drivers/usb/core/generic.c
@@ -184,7 +184,7 @@
/* if this is only an unbind, not a physical disconnect, then
* unconfigure the device */
if (udev->actconfig)
- usb_set_configuration(udev, 0);
+ usb_set_configuration(udev, -1);
usb_remove_sysfs_dev_files(udev);
}