USB: increase usbdevfs max isoc buffer size

The current limit only allows isochronous transfers up to 32kbyte/urb,
updating this to 192 kbyte/urb improves the reliability of the
transfer. USB 2.0 transfer is possible with 32kbyte but increases the
chance of corrupted/incomplete data when the system is performing some
other tasks in the background.

http://www.spinics.net/lists/linux-usb/msg19955.htmlSigned-off-by: NMarkus Rechberger <mrechberger@gmail.com>
Cc: Oliver Neukum <oliver@neukum.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/usb/core/devio.c

@@ -1091,7 +1091,8 @@ static int proc_do_submiturb(struct dev_state *ps, struct usbdevfs_urb *uurb,
 			}
 			totlen += isopkt[u].length;
 		}
-		if (totlen > 32768) {
+		/* 3072 * 64 microframes */
+		if (totlen > 196608) {
 			kfree(isopkt);
 			return -EINVAL;
 		}