[PATCH 3.2 46/61] Input: xpad - don't depend on endpoint order

[Ben Hutchings <ben@decadent.org.uk>]

3.2.96-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Cameron Gutman <aicommander@gmail.com>

commit c01b5e7464f0cf20936d7467c7528163c4e2782d upstream.

The order of endpoints is well defined on official Xbox pads, but
we have found at least one 3rd-party pad that doesn't follow the
standard ("Titanfall 2 Xbox One controller" 0e6f:0165).

Fortunately, we get lucky with this specific pad because it uses
endpoint addresses that differ only by direction. We know that
there are other pads out where this is not true, so let's go
ahead and fix this.

Signed-off-by: Cameron Gutman <aicommander@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
[bwh: Backported to 3.2:
 - Use 'fail3' label in case of failure
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
--- a/drivers/input/joystick/xpad.c
+++ b/drivers/input/joystick/xpad.c
@@ -675,10 +675,9 @@ exit:
 		    __func__, retval);
 }
 
-static int xpad_init_output(struct usb_interface *intf, struct usb_xpad *xpad)
+static int xpad_init_output(struct usb_interface *intf, struct usb_xpad *xpad,
+			struct usb_endpoint_descriptor *ep_irq_out)
 {
-	struct usb_endpoint_descriptor *ep_irq_out;
-	int ep_irq_out_idx;
 	int error;
 
 	if (xpad->xtype == XTYPE_UNKNOWN)
@@ -699,10 +698,6 @@ static int xpad_init_output(struct usb_i
 		goto fail2;
 	}
 
-	/* Xbox One controller has in/out endpoints swapped. */
-	ep_irq_out_idx = xpad->xtype == XTYPE_XBOXONE ? 0 : 1;
-	ep_irq_out = &intf->cur_altsetting->endpoint[ep_irq_out_idx].desc;
-
 	usb_fill_int_urb(xpad->irq_out, xpad->udev,
 			 usb_sndintpipe(xpad->udev, ep_irq_out->bEndpointAddress),
 			 xpad->odata, XPAD_PKT_LEN,
@@ -956,8 +951,7 @@ static int xpad_probe(struct usb_interfa
 	struct usb_device *udev = interface_to_usbdev(intf);
 	struct usb_xpad *xpad;
 	struct input_dev *input_dev;
-	struct usb_endpoint_descriptor *ep_irq_in;
-	int ep_irq_in_idx;
+	struct usb_endpoint_descriptor *ep_irq_in, *ep_irq_out;
 	int i, error;
 
 	if (intf->cur_altsetting->desc.bNumEndpoints != 2)
@@ -1073,7 +1067,24 @@ static int xpad_probe(struct usb_interfa
 			xpad_set_up_abs(input_dev, xpad_abs_triggers[i]);
 	}
 
-	error = xpad_init_output(intf, xpad);
+	ep_irq_in = ep_irq_out = NULL;
+
+	for (i = 0; i < 2; i++) {
+		struct usb_endpoint_descriptor *ep =
+				&intf->cur_altsetting->endpoint[i].desc;
+
+		if (usb_endpoint_dir_in(ep))
+			ep_irq_in = ep;
+		else
+			ep_irq_out = ep;
+	}
+
+	if (!ep_irq_in || !ep_irq_out) {
+		error = -ENODEV;
+		goto fail3;
+	}
+
+	error = xpad_init_output(intf, xpad, ep_irq_out);
 	if (error)
 		goto fail3;
 
@@ -1085,10 +1096,6 @@ static int xpad_probe(struct usb_interfa
 	if (error)
 		goto fail5;
 
-	/* Xbox One controller has in/out endpoints swapped. */
-	ep_irq_in_idx = xpad->xtype == XTYPE_XBOXONE ? 1 : 0;
-	ep_irq_in = &intf->cur_altsetting->endpoint[ep_irq_in_idx].desc;
-
 	usb_fill_int_urb(xpad->irq_in, udev,
 			 usb_rcvintpipe(udev, ep_irq_in->bEndpointAddress),
 			 xpad->idata, XPAD_PKT_LEN, xpad_irq_in,