HID: multitouch: Add ELAN production request when resume.

Add ELAN production request when resume.

Some Elan legacy devices require SET_IDLE to be set on resume.
It should be safe to send it to other devices too.
Tested on 3M, Stantum, Cypress, Zytronic, eGalax, and Elan panels.

Suggested by Benjamin Tissoires <benjamin.tissoires@enac.fr>

Signed-off-by: Scott Liu <scott.liu@emc.com.tw>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
index 4a8048d..e170112 100644
--- a/drivers/hid/hid-multitouch.c
+++ b/drivers/hid/hid-multitouch.c
@@ -765,6 +765,32 @@
 	mt_set_input_mode(hdev);
 	return 0;
 }
+
+static int mt_resume(struct hid_device *hdev)
+{
+	struct usb_interface *intf;
+	struct usb_host_interface *interface;
+	struct usb_device *dev;
+
+	if (hdev->bus != BUS_USB)
+		return 0;
+
+	intf = to_usb_interface(hdev->dev.parent);
+	interface = intf->cur_altsetting;
+	dev = hid_to_usb_dev(hdev);
+
+	/* Some Elan legacy devices require SET_IDLE to be set on resume.
+	 * It should be safe to send it to other devices too.
+	 * Tested on 3M, Stantum, Cypress, Zytronic, eGalax, and Elan panels. */
+
+	usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
+			HID_REQ_SET_IDLE,
+			USB_TYPE_CLASS | USB_RECIP_INTERFACE,
+			0, interface->desc.bInterfaceNumber,
+			NULL, 0, USB_CTRL_SET_TIMEOUT);
+
+	return 0;
+}
 #endif
 
 static void mt_remove(struct hid_device *hdev)
@@ -1102,6 +1128,7 @@
 	.event = mt_event,
 #ifdef CONFIG_PM
 	.reset_resume = mt_reset_resume,
+	.resume = mt_resume,
 #endif
 };