Commit 99688ecf authored Dec 04, 2014 by Alan Stern Committed by Greg Kroah-Hartman Jan 27, 2015

USB: EHCI: fix initialization bug in iso_stream_schedule()



commit 6d89252a998a695ecb0348fc2d717dc33d90cae9 upstream.

Commit c3ee9b76 (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: c3ee9b76
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>

parent 72934919

drivers/usb/host/ehci-sched.c

+4 −4

Original line number	Original line	Diff line number	Diff line
	@@ -1581,6 +1581,10 @@ iso_stream_schedule (
	else		else
	next = (now + 2 + 7) & ~0x07; /* full frame cache */		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		* Use ehci->last_iso_frame as the base. There can't be any
	* TDs scheduled for earlier than that.		* TDs scheduled for earlier than that.
	@@ -1671,10 +1675,6 @@ iso_stream_schedule (
	urb->start_frame = start & (mod - 1);		urb->start_frame = start & (mod - 1);
	if (!stream->highspeed)		if (!stream->highspeed)
	urb->start_frame >>= 3;		urb->start_frame >>= 3;

	/* Make sure scan_isoc() sees these */
	if (ehci->isoc_count == 0)
	ehci->last_iso_frame = now >> 3;
	return status;		return status;

	fail:		fail: