USB: EHCI: update toggle state for linked QHs
This patch (as1245) fixes a bug in ehci-hcd. When an URB is queued
for an endpoint whose QH is already in the LINKED state, the QH
doesn't get refreshed. As a result, if usb_clear_halt() was called
during the time that the QH was linked but idle, the data toggle value
in the QH doesn't get reset.
The symptom is that after a clear_halt, data gets lost and transfers
time out. This problem is starting to show up now because the
"ehci-hcd unlink speedups" patch causes QHs with no queued URBs to
remain linked for a suitable time.
The patch utilizes the new endpoint_reset mechanism to fix the
problem. When an endpoint is reset, the new method forcibly unlinks
the QH (if necessary) and safely updates the toggle value. This
allows qh_update() to be simplified and avoids using usb_device's
toggle bits in a rather unintuitive way.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: David Brownell <david-b@pacbell.net>
Tested-by: David <david@unsolicited.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index a2ca9cb..2b72473 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -1024,6 +1024,51 @@
return;
}
+static void
+ehci_endpoint_reset(struct usb_hcd *hcd, struct usb_host_endpoint *ep)
+{
+ struct ehci_hcd *ehci = hcd_to_ehci(hcd);
+ struct ehci_qh *qh;
+ int eptype = usb_endpoint_type(&ep->desc);
+
+ if (eptype != USB_ENDPOINT_XFER_BULK && eptype != USB_ENDPOINT_XFER_INT)
+ return;
+
+ rescan:
+ spin_lock_irq(&ehci->lock);
+ qh = ep->hcpriv;
+
+ /* For Bulk and Interrupt endpoints we maintain the toggle state
+ * in the hardware; the toggle bits in udev aren't used at all.
+ * When an endpoint is reset by usb_clear_halt() we must reset
+ * the toggle bit in the QH.
+ */
+ if (qh) {
+ if (!list_empty(&qh->qtd_list)) {
+ WARN_ONCE(1, "clear_halt for a busy endpoint\n");
+ } else if (qh->qh_state == QH_STATE_IDLE) {
+ qh->hw_token &= ~cpu_to_hc32(ehci, QTD_TOGGLE);
+ } else {
+ /* It's not safe to write into the overlay area
+ * while the QH is active. Unlink it first and
+ * wait for the unlink to complete.
+ */
+ if (qh->qh_state == QH_STATE_LINKED) {
+ if (eptype == USB_ENDPOINT_XFER_BULK) {
+ unlink_async(ehci, qh);
+ } else {
+ intr_deschedule(ehci, qh);
+ (void) qh_schedule(ehci, qh);
+ }
+ }
+ spin_unlock_irq(&ehci->lock);
+ schedule_timeout_uninterruptible(1);
+ goto rescan;
+ }
+ }
+ spin_unlock_irq(&ehci->lock);
+}
+
static int ehci_get_frame (struct usb_hcd *hcd)
{
struct ehci_hcd *ehci = hcd_to_ehci (hcd);