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Commit b761d9d8 authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman
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[PATCH] UHCI: Work around old Intel bug 



Some old Intel UHCI controllers have a bug that has shown up in a few
systems (the PIIX3 "Neptune" chip set).  Until now there has not been
any simple way to work around the bug, but the lastest changes in
uhci-hcd have made it easy.  This patch (as684) adds the work-around.

Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 84afddd7

drivers/usb/host/uhci-q.c

+15 −1
Original line number Diff line number Diff line
@@ -13,7 +13,7 @@ 
 * (C) Copyright 2000 Yggdrasil Computing, Inc. (port of new PCI interface

 *               support from usb-ohci.c by Adam Richter, adam@yggdrasil.com).

 * (C) Copyright 1999 Gregory P. Smith (from usb-ohci.c)

 * (C) Copyright 2004-2005 Alan Stern, stern@rowland.harvard.edu

 * (C) Copyright 2004-2006 Alan Stern, stern@rowland.harvard.edu

 */
@@ -1287,6 +1287,11 @@ static void uhci_scan_qh(struct uhci_hcd *uhci, struct uhci_qh *qh, 
 * Check for queues that have made some forward progress.

 * Returns 0 if the queue is not Isochronous, is ACTIVE, and

 * has not advanced since last examined; 1 otherwise.

 *

 * Early Intel controllers have a bug which causes qh->element sometimes

 * not to advance when a TD completes successfully.  The queue remains

 * stuck on the inactive completed TD.  We detect such cases and advance

 * the element pointer by hand.

 */

static int uhci_advance_check(struct uhci_hcd *uhci, struct uhci_qh *qh)

{
@@ -1327,6 +1332,15 @@ static int uhci_advance_check(struct uhci_hcd *uhci, struct uhci_qh *qh) 
	/* The queue hasn't advanced; check for timeout */

	if (!qh->wait_expired && time_after(jiffies,

			qh->advance_jiffies + QH_WAIT_TIMEOUT)) {



		/* Detect the Intel bug and work around it */

		if (qh->post_td && qh_element(qh) ==

				cpu_to_le32(qh->post_td->dma_handle)) {

			qh->element = qh->post_td->link;

			qh->advance_jiffies = jiffies;

			return 1;

		}



		qh->wait_expired = 1;



		/* If the current URB wants FSBR, unlink it temporarily