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From: Greg KH on 30 Mar 2010 20:10
2.6.32-stable review patch. If anyone has any objections, please let us know.

------------------

From: Clemens Ladisch <clemens(a)ladisch.de>

commit 92bc3648e6027384479852b770a542722fadee7c upstream.

When isochronous URBs are shorter than one frame and when more than one
ITD in a frame has been completed before the interrupt can be handled,
scan_periodic() completes the URBs in the order in which they are found
in the descriptor list. Therefore, the descriptor list must contain the
ITDs in the correct order, i.e., a new ITD must be linked in after any
previous ITDs of the same endpoint.

This should fix garbled capture data in the USB audio drivers.

Signed-off-by: Clemens Ladisch <clemens(a)ladisch.de>
Reported-by: Colin Fletcher <colin.m.fletcher(a)googlemail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)suse.de>

---
drivers/usb/host/ehci-sched.c | 24 +++++++++++++++++++-----
1 file changed, 19 insertions(+), 5 deletions(-)

--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -1553,13 +1553,27 @@ itd_patch(
static inline void
itd_link (struct ehci_hcd *ehci, unsigned frame, struct ehci_itd *itd)
{
- /* always prepend ITD/SITD ... only QH tree is order-sensitive */
- itd->itd_next = ehci->pshadow [frame];
- itd->hw_next = ehci->periodic [frame];
- ehci->pshadow [frame].itd = itd;
+ union ehci_shadow *prev = &ehci->pshadow[frame];
+ __hc32 *hw_p = &ehci->periodic[frame];
+ union ehci_shadow here = *prev;
+ __hc32 type = 0;
+
+ /* skip any iso nodes which might belong to previous microframes */
+ while (here.ptr) {
+ type = Q_NEXT_TYPE(ehci, *hw_p);
+ if (type == cpu_to_hc32(ehci, Q_TYPE_QH))
+ break;
+ prev = periodic_next_shadow(ehci, prev, type);
+ hw_p = shadow_next_periodic(ehci, &here, type);
+ here = *prev;
+ }
+
+ itd->itd_next = here;
+ itd->hw_next = *hw_p;
+ prev->itd = itd;
itd->frame = frame;
wmb ();
- ehci->periodic[frame] = cpu_to_hc32(ehci, itd->itd_dma | Q_TYPE_ITD);
+ *hw_p = cpu_to_hc32(ehci, itd->itd_dma | Q_TYPE_ITD);
}

/* fit urb's itds into the selected schedule slot; activate as needed */


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