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.html

Signed-off-by: Markus Rechberger <mrechberger@gmail.com>
Cc: Oliver Neukum <oliver@neukum.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index a1add77..71514be 100644 (file)
--- a/drivers/usb/core/devio.c
+++ b/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;
                }