USB: EHCI: fix initialization bug in iso_stream_schedule()

commit 6d89252a998a695ecb0348fc2d717dc33d90cae9 upstream.

Commit c3ee9b76aa93 (EHCI: improved logic for isochronous scheduling)
introduced the idea of using ehci->last_iso_frame as the origin (or
base) for the circular calculations involved in modifying the
isochronous schedule.  However, the new code it added used
ehci->last_iso_frame before the value was properly initialized.  This
patch rectifies the mistake by moving the initialization lines earlier
in iso_stream_schedule().

This fixes Bugzilla #72891.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Fixes: c3ee9b76aa93
Reported-by: Joe Bryant <tenminjoe@yahoo.com>
Tested-by: Joe Bryant <tenminjoe@yahoo.com>
Tested-by: Martin Long <martin@longhome.co.uk>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>

diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index 85dd24e..8ecf164 100644 (file)
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -1384,6 +1384,10 @@ iso_stream_schedule (
 
        now = ehci_read_frame_index(ehci) & (mod - 1);
 
+       /* If needed, initialize last_iso_frame so that this URB will be seen */
+       if (ehci->isoc_count == 0)
+               ehci->last_iso_frame = now >> 3;
+
        /* Typical case: reuse current schedule, stream is still active.
         * Hopefully there are no gaps from the host falling behind
         * (irq delays etc).  If there are, the behavior depends on
@@ -1493,10 +1497,6 @@ iso_stream_schedule (
        urb->start_frame = stream->next_uframe;
        if (!stream->highspeed)
                urb->start_frame >>= 3;
-
-       /* Make sure scan_isoc() sees these */
-       if (ehci->isoc_count == 0)
-               ehci->last_iso_frame = now >> 3;
        return 0;
 
  fail: