USB: OHCI: add check for stopped frame counter

This patch adds an extra check to ohci-hcd's I/O watchdog routine.  If
the controller stops updating the frame counter, we will assume it is
dead.  But there has to be an exception: Some controllers stop the
frame counter when no ports are connected.  Check to make sure there
is at least one active port before deciding the controller is dead.

(This test may appear racy, but it isn't.  Enabling a newly connected
port takes several milliseconds, during which time the frame counter
must advance.)
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Tested-by: Dennis New <dennisn@dennisn.linuxd.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/ohci-hcd.c

@@ -230,9 +230,11 @@ static int ohci_urb_enqueue (
 
 		/* Start up the I/O watchdog timer, if it's not running */
 		if (!timer_pending(&ohci->io_watchdog) &&
-				list_empty(&ohci->eds_in_use))
+				list_empty(&ohci->eds_in_use)) {
+			ohci->prev_frame_no = ohci_frame_no(ohci);
 			mod_timer(&ohci->io_watchdog,
 					jiffies + IO_WATCHDOG_DELAY);
+		}
 		list_add(&ed->in_use_list, &ohci->eds_in_use);
 
 		if (ed->type == PIPE_ISOCHRONOUS) {
@@ -727,6 +729,7 @@ static void io_watchdog_func(unsigned long _ohci)
 	u32		head;
 	struct ed	*ed;
 	struct td	*td, *td_start, *td_next;
+	unsigned	frame_no;
 	unsigned long	flags;
 
 	spin_lock_irqsave(&ohci->lock, flags);
@@ -742,6 +745,7 @@ static void io_watchdog_func(unsigned long _ohci)
 	if (!(status & OHCI_INTR_WDH) && ohci->wdh_cnt == ohci->prev_wdh_cnt) {
 		if (ohci->prev_donehead) {
 			ohci_err(ohci, "HcDoneHead not written back; disabled\n");
+ died:
 			usb_hc_died(ohci_to_hcd(ohci));
 			ohci_dump(ohci);
 			ohci_shutdown(ohci_to_hcd(ohci));
@@ -802,7 +806,35 @@ static void io_watchdog_func(unsigned long _ohci)
 	ohci_work(ohci);
 
 	if (ohci->rh_state == OHCI_RH_RUNNING) {
+
+		/*
+		 * Sometimes a controller just stops working.  We can tell
+		 * by checking that the frame counter has advanced since
+		 * the last time we ran.
+		 *
+		 * But be careful: Some controllers violate the spec by
+		 * stopping their frame counter when no ports are active.
+		 */
+		frame_no = ohci_frame_no(ohci);
+		if (frame_no == ohci->prev_frame_no) {
+			int		active_cnt = 0;
+			int		i;
+			unsigned	tmp;
+
+			for (i = 0; i < ohci->num_ports; ++i) {
+				tmp = roothub_portstatus(ohci, i);
+				/* Enabled and not suspended? */
+				if ((tmp & RH_PS_PES) && !(tmp & RH_PS_PSS))
+					++active_cnt;
+			}
+
+			if (active_cnt > 0) {
+				ohci_err(ohci, "frame counter not updating; disabled\n");
+				goto died;
+			}
+		}
 		if (!list_empty(&ohci->eds_in_use)) {
+			ohci->prev_frame_no = frame_no;
 			ohci->prev_wdh_cnt = ohci->wdh_cnt;
 			ohci->prev_donehead = ohci_readl(ohci,
 					&ohci->regs->donehead);

drivers/usb/host/ohci.h

@@ -421,6 +421,7 @@ struct ohci_hcd {
 
 	// there are also chip quirks/bugs in init logic
 
+	unsigned		prev_frame_no;
 	unsigned		wdh_cnt, prev_wdh_cnt;
 	u32			prev_donehead;
 	struct timer_list	io_watchdog;