HID: handle all multitouch devices through hid-multitouch

When the quirk HID_QUIRK_MULTITOUCH is present and when hid-multitouch
is loaded, let's pass the device to hid-multitouch even if it has
not been registered in hid-multitouch.

If any other driver wants to take precedence over hid-multitouch,
the usual way of adding it to hid_have_special_driver will work as
the quirk HID_QUIRK_MULTITOUCH won't be set by the generic hid layer.
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@enac.fr>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-core.c

@@ -1232,7 +1232,6 @@ int hid_connect(struct hid_device *hdev, unsigned int connect_mask)
 		hdev->claimed |= HID_CLAIMED_INPUT;
 	if (hdev->quirks & HID_QUIRK_MULTITOUCH) {
 		/* this device should be handled by hid-multitouch, skip it */
-		hdev->quirks &= ~HID_QUIRK_MULTITOUCH;
 		return -ENODEV;
 	}
 
@@ -1667,6 +1666,10 @@ static int hid_bus_match(struct device *dev, struct device_driver *drv)
 	struct hid_driver *hdrv = container_of(drv, struct hid_driver, driver);
 	struct hid_device *hdev = container_of(dev, struct hid_device, dev);
 
+	if ((hdev->quirks & HID_QUIRK_MULTITOUCH) &&
+		!strncmp(hdrv->name, "hid-multitouch", 14))
+		return 1;
+
 	if (!hid_match_device(hdev, hdrv))
 		return 0;
 
@@ -1691,9 +1694,12 @@ static int hid_device_probe(struct device *dev)
 	if (!hdev->driver) {
 		id = hid_match_device(hdev, hdrv);
 		if (id == NULL) {
+			if (!((hdev->quirks & HID_QUIRK_MULTITOUCH) &&
+				!strncmp(hdrv->name, "hid-multitouch", 14))) {
 				ret = -ENODEV;
 				goto unlock;
 			}
+		}
 
 		hdev->driver = hdrv;
 		if (hdrv->probe) {

drivers/hid/hid-multitouch.c

@@ -637,17 +637,20 @@ static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
 	struct mt_device *td;
 	struct mt_class *mtclass = mt_classes; /* MT_CLS_DEFAULT */
 
+	if (id) {
 		for (i = 0; mt_classes[i].name ; i++) {
 			if (id->driver_data == mt_classes[i].name) {
 				mtclass = &(mt_classes[i]);
 				break;
 			}
 		}
+	}
 
 	/* This allows the driver to correctly support devices
 	 * that emit events over several HID messages.
 	 */
 	hdev->quirks |= HID_QUIRK_NO_INPUT_SYNC;
+	hdev->quirks &= ~HID_QUIRK_MULTITOUCH;
 
 	td = kzalloc(sizeof(struct mt_device), GFP_KERNEL);
 	if (!td) {