[Qemu-devel] [5199] uhci: Change default transaction lifetime to 32 frames ( Max Krasnyansky)

[Qemu-devel] [5199] uhci: Change default transaction lifetime to 32 frames ( Max Krasnyansky)

[Anthony Liguori]

Revision: 5199
          http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=5199
Author:   aliguori
Date:     2008-09-11 19:42:00 +0000 (Thu, 11 Sep 2008)

Log Message:
-----------
uhci: Change default transaction lifetime to 32 frames (Max Krasnyansky)

Transaction lifetime was originally set to 10 frames. That was an arbitrary
number I picked without much thinking :).
I'm changing that to 32 frames because things like interrupt transfers
and such are scheduled at that rate. It seems like 1/32 is accepted as
lowest supported rate. OHCI, for example, defines exactly 32 interrupt
heads.

While testing USB webcam under XP I noticed that interrupt transactions were
being canceled and then resubmitted on a regular basis, which works but is a
waste of CPU cycles. This change fixes that.
All other devices I have are not affected.

Signed-off-by: Max Krasnyansky <maxk@kernel.org>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

Modified Paths:
--------------
    trunk/hw/usb-uhci.c

Modified: trunk/hw/usb-uhci.c
===================================================================
--- trunk/hw/usb-uhci.c	2008-09-11 18:16:02 UTC (rev 5198)
+++ trunk/hw/usb-uhci.c	2008-09-11 19:42:00 UTC (rev 5199)
@@ -781,7 +781,7 @@
     async = uhci_async_find_td(s, addr, td->token);
     if (async) {
         /* Already submitted */
-        async->valid = 10;
+        async->valid = 32;
 
         if (!async->done)
             return 1;