diff options
| author | Alan Stern <stern@rowland.harvard.edu> | 2006-05-12 11:41:59 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2006-06-21 15:04:11 -0700 |
| commit | b761d9d867bcc29e8de3e62d1d72b27e75078ca6 (patch) | |
| tree | 40b8f2e530bd9bbece14007a3d887bbe12e8afde | |
| parent | 84afddd7ac58adad00cb0e50d0af25fcf825668b (diff) | |
[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: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | drivers/usb/host/uhci-q.c | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/drivers/usb/host/uhci-q.c b/drivers/usb/host/uhci-q.c index 2be84b3b40f..76b0a9e95a7 100644 --- a/drivers/usb/host/uhci-q.c +++ b/drivers/usb/host/uhci-q.c @@ -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 @@ restart: * 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 |