USB: EHCI: fix ITD list order

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@ladisch.de>
Reported-by: Colin Fletcher <colin.m.fletcher@googlemail.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 19 insertions, 5 deletions

diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index 39340ae00ac4..cd1e8bf5327e 100644
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -1565,13 +1565,27 @@ 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 */