[Qemu-devel] [PATCH] uhci: Change default transaction lifetime to 32 frames

[Max Krasnyansky <maxk@kernel.org>]

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>
---
 hw/usb-uhci.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/hw/usb-uhci.c b/hw/usb-uhci.c
index 62c743d..b90cf78 100644
--- a/hw/usb-uhci.c
+++ b/hw/usb-uhci.c
@@ -781,7 +781,7 @@ static int uhci_handle_td(UHCIState *s, uint32_t addr, UHCI_TD *td, uint32_t *in
     async = uhci_async_find_td(s, addr, td->token);
     if (async) {
         /* Already submitted */
-        async->valid = 10;
+        async->valid = 32;
 
         if (!async->done)
             return 1;
-- 
1.5.5.1