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USB: EHCI: fix initialization bug in iso_stream_schedule() 

commit 6d89252a99 upstream.

Commit c3ee9b76aa (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: c3ee9b76aa
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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alan Stern 2014-12-04 10:21:56 -05:00 committed by Greg Kroah-Hartman
parent 23c631c3db
commit 727cc57106
1 changed files with 4 additions and 4 deletions
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8
drivers/usb/host/ehci-sched.c
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@ -1581,6 +1581,10 @@ iso_stream_schedule (
else
next = (now + 2 + 7) & ~0x07; /* full frame cache */
/* If needed, initialize last_iso_frame so that this URB will be seen */
if (ehci->isoc_count == 0)
ehci->last_iso_frame = now >> 3;
/*
* Use ehci->last_iso_frame as the base. There can't be any
* TDs scheduled for earlier than that.
@ -1671,10 +1675,6 @@ iso_stream_schedule (
urb->start_frame = start & (mod - 1);
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 status;
fail: