On Tuesday 21 April 2009, Dan Streetman wrote:
>
> Hopefully this description is ok? ;-)
Yes, much better; thanks.
Acked-by: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx>
> Without this patch, the driver won't check that the last fully-occupied
> uframe for a new split transaction was vacant beforehand. This can
> lead to a situation in which the first 188 bytes of a 192-byte
> isochronous transfer are scheduled in the same uframe as an existing
> interrupt transfer. The resulting schedule looks like this:
>
> uframe 0: 188-byte isoc-OUT SSPLIT, 8-byte int-IN SSPLIT
> uframe 1: 4-byte isoc-OUT SSPLIT
>
> The SSPLITs are intermingled, causing an error in the downstream hub's
> TT.
>
> If you are having problems with devices or hub ports resetting, or failed
> interrupt transfers, when you start using a USB audio or video (Isochronous)
> device, this patch may help.
>
>
> Signed-off-by: Dan Streetman <ddstreet@xxxxxxxx>
> Reported-by: Kung James <kong1191@xxxxxxxxx>
>
>
> --- a/drivers/usb/host/ehci-sched.c 2009-04-17 15:05:02.000000000 -0400
> +++ linux-2.6.30-rc2/drivers/usb/host/ehci-sched.c 2009-04-17 15:05:33.000000000 -0400
> @@ -323,7 +323,7 @@ static int tt_available (
> * already scheduled transactions
> */
> if (125 < usecs) {
> - int ufs = (usecs / 125) - 1;
> + int ufs = (usecs / 125);
> int i;
> for (i = uframe; i < (uframe + ufs) && i < 8; i++)
> if (0 < tt_usecs[i]) {
>
>
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