USB: EHCI: store reason for unlinking a QH

This patch replaces the "exception" bitflag in the ehci_qh structure
with a more explicit "unlink_reason" bitmask.  This is for use in the
following patch, where we will need to have a good idea of the
reason for unlinking a QH, not just "something exceptional happened".

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Tested-by: Michael Reutman <mreutman@epiqsolutions.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/ehci-hcd.c

@@ -911,7 +911,7 @@ static int ehci_urb_dequeue(struct usb_hcd *hcd, struct urb *urb, int status)
 		 */
 	} else {
 		qh = (struct ehci_qh *) urb->hcpriv;
-		qh->exception = 1;
+		qh->unlink_reason |= QH_UNLINK_REQUESTED;
 		switch (qh->qh_state) {
 		case QH_STATE_LINKED:
 			if (usb_pipetype(urb->pipe) == PIPE_INTERRUPT)
@@ -972,10 +972,13 @@ rescan:
 		goto done;
 	}
 
-	qh->exception = 1;
+	qh->unlink_reason |= QH_UNLINK_REQUESTED;
 	switch (qh->qh_state) {
 	case QH_STATE_LINKED:
-		WARN_ON(!list_empty(&qh->qtd_list));
+		if (list_empty(&qh->qtd_list))
+			qh->unlink_reason |= QH_UNLINK_QUEUE_EMPTY;
+		else
+			WARN_ON(1);
 		if (usb_endpoint_type(&ep->desc) != USB_ENDPOINT_XFER_INT)
 			start_unlink_async(ehci, qh);
 		else
@@ -1042,7 +1045,7 @@ ehci_endpoint_reset(struct usb_hcd *hcd, struct usb_host_endpoint *ep)
 			 * re-linking will call qh_refresh().
 			 */
 			usb_settoggle(qh->ps.udev, epnum, is_out, 0);
-			qh->exception = 1;
+			qh->unlink_reason |= QH_UNLINK_REQUESTED;
 			if (eptype == USB_ENDPOINT_XFER_BULK)
 				start_unlink_async(ehci, qh);
 			else

drivers/usb/host/ehci-q.c

@@ -394,6 +394,7 @@ qh_completions (struct ehci_hcd *ehci, struct ehci_qh *qh)
 					goto retry_xacterr;
 				}
 				stopped = 1;
+				qh->unlink_reason |= QH_UNLINK_HALTED;
 
 			/* magic dummy for some short reads; qh won't advance.
 			 * that silicon quirk can kick in with this dummy too.
@@ -408,6 +409,7 @@ qh_completions (struct ehci_hcd *ehci, struct ehci_qh *qh)
 					&& !(qtd->hw_alt_next
 						& EHCI_LIST_END(ehci))) {
 				stopped = 1;
+				qh->unlink_reason |= QH_UNLINK_SHORT_READ;
 			}
 
 		/* stop scanning when we reach qtds the hc is using */
@@ -420,8 +422,10 @@ qh_completions (struct ehci_hcd *ehci, struct ehci_qh *qh)
 			stopped = 1;
 
 			/* cancel everything if we halt, suspend, etc */
-			if (ehci->rh_state < EHCI_RH_RUNNING)
+			if (ehci->rh_state < EHCI_RH_RUNNING) {
 				last_status = -ESHUTDOWN;
+				qh->unlink_reason |= QH_UNLINK_SHUTDOWN;
+			}
 
 			/* this qtd is active; skip it unless a previous qtd
 			 * for its urb faulted, or its urb was canceled.
@@ -538,10 +542,10 @@ qh_completions (struct ehci_hcd *ehci, struct ehci_qh *qh)
 	 * except maybe high bandwidth ...
 	 */
 	if (stopped != 0 || hw->hw_qtd_next == EHCI_LIST_END(ehci))
-		qh->exception = 1;
+		qh->unlink_reason |= QH_UNLINK_DUMMY_OVERLAY;
 
 	/* Let the caller know if the QH needs to be unlinked. */
-	return qh->exception;
+	return qh->unlink_reason;
 }
 
 /*-------------------------------------------------------------------------*/
@@ -1003,7 +1007,7 @@ static void qh_link_async (struct ehci_hcd *ehci, struct ehci_qh *qh)
 
 	qh->qh_state = QH_STATE_LINKED;
 	qh->xacterrs = 0;
-	qh->exception = 0;
+	qh->unlink_reason = 0;
 	/* qtd completions reported later by interrupt */
 
 	enable_async(ehci);
@@ -1395,6 +1399,7 @@ static void unlink_empty_async(struct ehci_hcd *ehci)
 
 	/* If nothing else is being unlinked, unlink the last empty QH */
 	if (list_empty(&ehci->async_unlink) && qh_to_unlink) {
+		qh_to_unlink->unlink_reason |= QH_UNLINK_QUEUE_EMPTY;
 		start_unlink_async(ehci, qh_to_unlink);
 		--count;
 	}

drivers/usb/host/ehci-sched.c

@@ -595,7 +595,7 @@ static void qh_link_periodic(struct ehci_hcd *ehci, struct ehci_qh *qh)
 	}
 	qh->qh_state = QH_STATE_LINKED;
 	qh->xacterrs = 0;
-	qh->exception = 0;
+	qh->unlink_reason = 0;
 
 	/* update per-qh bandwidth for debugfs */
 	ehci_to_hcd(ehci)->self.bandwidth_allocated += qh->ps.bw_period

drivers/usb/host/ehci-timer.c

@@ -237,6 +237,7 @@ static void ehci_handle_start_intr_unlinks(struct ehci_hcd *ehci)
 				ehci->intr_unlink_wait_cycle))
 			break;
 		list_del_init(&qh->unlink_node);
+		qh->unlink_reason |= QH_UNLINK_QUEUE_EMPTY;
 		start_unlink_intr(ehci, qh);
 	}
 

drivers/usb/host/ehci.h

@@ -432,13 +432,19 @@ struct ehci_qh {
 	u8			xacterrs;	/* XactErr retry counter */
 #define	QH_XACTERR_MAX		32		/* XactErr retry limit */
 
+	u8			unlink_reason;
+#define QH_UNLINK_HALTED	0x01		/* Halt flag is set */
+#define QH_UNLINK_SHORT_READ	0x02		/* Recover from a short read */
+#define QH_UNLINK_DUMMY_OVERLAY	0x04		/* QH overlayed the dummy TD */
+#define QH_UNLINK_SHUTDOWN	0x08		/* The HC isn't running */
+#define QH_UNLINK_QUEUE_EMPTY	0x10		/* Reached end of the queue */
+#define QH_UNLINK_REQUESTED	0x20		/* Disable, reset, or dequeue */
+
 	u8			gap_uf;		/* uframes split/csplit gap */
 
 	unsigned		is_out:1;	/* bulk or intr OUT */
 	unsigned		clearing_tt:1;	/* Clear-TT-Buf in progress */
 	unsigned		dequeue_during_giveback:1;
-	unsigned		exception:1;	/* got a fault, or an unlink
-						   was requested */
 	unsigned		should_be_inactive:1;
 };