[PATCH] USB: proper evaluation of the union descriptor for CDC ACM

this changes acm_probe() to using the proper union descriptor.
It contains the workaround David suggested. Please apply.

  - fix probing to use cdc union descriptor
Signed-off-by: Oliver Neukum <oliver@neukum.name>
Signed-off-by: Vojtech Pavlik <vojtech@suse.cz>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

drivers/usb/class/cdc-acm.h

+/*
+ *
+ * Includes for cdc-acm.c
+ *
+ * Mainly take from usbnet's cdc-ether part
+ *
+ */
+
+/*
+ * CMSPAR, some architectures can't have space and mark parity.
+ */
+
+#ifndef CMSPAR
+#define CMSPAR			0
+#endif
+
+/*
+ * Major and minor numbers.
+ */
+
+#define ACM_TTY_MAJOR		166
+#define ACM_TTY_MINORS		32
+
+/*
+ * Requests.
+ */
+
+#define USB_RT_ACM		(USB_TYPE_CLASS | USB_RECIP_INTERFACE)
+
+#define ACM_REQ_COMMAND		0x00
+#define ACM_REQ_RESPONSE	0x01
+#define ACM_REQ_SET_FEATURE	0x02
+#define ACM_REQ_GET_FEATURE	0x03
+#define ACM_REQ_CLEAR_FEATURE	0x04
+
+#define ACM_REQ_SET_LINE	0x20
+#define ACM_REQ_GET_LINE	0x21
+#define ACM_REQ_SET_CONTROL	0x22
+#define ACM_REQ_SEND_BREAK	0x23
+
+/*
+ * IRQs.
+ */
+
+#define ACM_IRQ_NETWORK		0x00
+#define ACM_IRQ_LINE_STATE	0x20
+
+/*
+ * Output control lines.
+ */
+
+#define ACM_CTRL_DTR		0x01
+#define ACM_CTRL_RTS		0x02
+
+/*
+ * Input control lines and line errors.
+ */
+
+#define ACM_CTRL_DCD		0x01
+#define ACM_CTRL_DSR		0x02
+#define ACM_CTRL_BRK		0x04
+#define ACM_CTRL_RI		0x08
+
+#define ACM_CTRL_FRAMING	0x10
+#define ACM_CTRL_PARITY		0x20
+#define ACM_CTRL_OVERRUN	0x40
+
+/*
+ * Line speed and caracter encoding.
+ */
+
+struct acm_line {
+	__u32 speed;
+	__u8 stopbits;
+	__u8 parity;
+	__u8 databits;
+} __attribute__ ((packed));
+
+/*
+ * Internal driver structures.
+ */
+
+struct acm {
+	struct usb_device *dev;				/* the corresponding usb device */
+	struct usb_interface *control;			/* control interface */
+	struct usb_interface *data;			/* data interface */
+	struct tty_struct *tty;				/* the corresponding tty */
+	struct urb *ctrlurb, *readurb, *writeurb;	/* urbs */
+	struct acm_line line;				/* line coding (bits, stop, parity) */
+	struct work_struct work;			/* work queue entry for line discipline waking up */
+	struct tasklet_struct bh;			/* rx processing */
+	unsigned int ctrlin;				/* input control lines (DCD, DSR, RI, break, overruns) */
+	unsigned int ctrlout;				/* output control lines (DTR, RTS) */
+	unsigned int writesize;				/* max packet size for the output bulk endpoint */
+	unsigned int used;				/* someone has this acm's device open */
+	unsigned int minor;				/* acm minor number */
+	unsigned char throttle;				/* throttled by tty layer */
+	unsigned char clocal;				/* termios CLOCAL */
+};
+
+/* "Union Functional Descriptor" from CDC spec 5.2.3.X */
+struct union_desc {
+	u8	bLength;
+	u8	bDescriptorType;
+	u8	bDescriptorSubType;
+
+	u8	bMasterInterface0;
+	u8	bSlaveInterface0;
+	/* ... and there could be other slave interfaces */
+} __attribute__ ((packed));
+
+#define CDC_UNION_TYPE		0x06
+#define CDC_DATA_INTERFACE_TYPE	0x0a
+