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[PATCH] UHCI: Work around old Intel bug

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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: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Alan Stern 2006-05-12 11:41:59 -04:00 committed by Greg Kroah-Hartman
parent 84afddd7ac
commit b761d9d867
1 changed files with 15 additions and 1 deletions
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16
drivers/usb/host/uhci-q.c
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@ -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