USB: core: add device-qualifier quirk

commit 2a159389 upstream.

Add new quirk for devices that cannot handle requests for the
device_qualifier descriptor.

A USB-2.0 compliant device must respond to requests for the
device_qualifier descriptor (even if it's with a request error), but at
least one device is known to misbehave after such a request.
Suggested-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ luis: prereq for the following Elan touchscreen patches ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

drivers/usb/core/hub.c

@@ -4524,6 +4524,9 @@ check_highspeed (struct usb_hub *hub, struct usb_device *udev, int port1)
 	struct usb_qualifier_descriptor	*qual;
 	int				status;
 
+	if (udev->quirks & USB_QUIRK_DEVICE_QUALIFIER)
+		return;
+
 	qual = kmalloc (sizeof *qual, GFP_KERNEL);
 	if (qual == NULL)
 		return;

include/linux/usb/quirks.h

@@ -33,4 +33,7 @@
 /* device generates spurious wakeup, ignore remote wakeup capability */
 #define USB_QUIRK_IGNORE_REMOTE_WAKEUP	0x00000200
 
+/* device can't handle device_qualifier descriptor requests */
+#define USB_QUIRK_DEVICE_QUALIFIER	0x00000100
+
 #endif /* __LINUX_USB_QUIRKS_H */