USB: EHCI: add new root-hub state: STOPPING

This patch (as1571) adds a new state for ehci-hcd's root hubs:
EHCI_RH_STOPPING.  This value is used at times when the root hub is
being stopped and we don't know whether or not the hardware has
finished all its DMA yet.

Although the purpose may not be apparent, this distinction will come
in useful later on.  Future patches will avoid actions that depend on
the root hub being operational (like turning on the async or periodic
schedules) when they see the state is EHCI_RH_STOPPING.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/ehci-dbg.c

@@ -706,6 +706,8 @@ static const char *rh_state_string(struct ehci_hcd *ehci)
 		return "suspended";
 	case EHCI_RH_RUNNING:
 		return "running";
+	case EHCI_RH_STOPPING:
+		return "stopping";
 	}
 	return "?";
 }

drivers/usb/host/ehci-hcd.c

@@ -357,10 +357,8 @@ static void ehci_quiesce (struct ehci_hcd *ehci)
 {
 	u32	temp;
 
-#ifdef DEBUG
 	if (ehci->rh_state != EHCI_RH_RUNNING)
-		BUG ();
-#endif
+		return;
 
 	/* wait for any schedule enables/disables to take effect */
 	temp = (ehci->command << 10) & (STS_ASS | STS_PSS);
@@ -494,6 +492,7 @@ static void ehci_shutdown(struct usb_hcd *hcd)
 	del_timer_sync(&ehci->iaa_watchdog);
 
 	spin_lock_irq(&ehci->lock);
+	ehci->rh_state = EHCI_RH_STOPPING;
 	ehci_silence_controller(ehci);
 	spin_unlock_irq(&ehci->lock);
 }
@@ -562,8 +561,7 @@ static void ehci_stop (struct usb_hcd *hcd)
 	del_timer_sync(&ehci->iaa_watchdog);
 
 	spin_lock_irq(&ehci->lock);
-	if (ehci->rh_state == EHCI_RH_RUNNING)
-		ehci_quiesce (ehci);
+	ehci_quiesce(ehci);
 
 	ehci_silence_controller(ehci);
 	ehci_reset (ehci);
@@ -951,6 +949,7 @@ static irqreturn_t ehci_irq (struct usb_hcd *hcd)
 	/* PCI errors [4.15.2.4] */
 	if (unlikely ((status & STS_FATAL) != 0)) {
 		ehci_err(ehci, "fatal error\n");
+		ehci->rh_state = EHCI_RH_STOPPING;
 		dbg_cmd(ehci, "fatal", cmd);
 		dbg_status(ehci, "fatal", status);
 		ehci_halt(ehci);
@@ -1026,7 +1025,7 @@ static int ehci_urb_enqueue (
 static void unlink_async (struct ehci_hcd *ehci, struct ehci_qh *qh)
 {
 	/* failfast */
-	if (ehci->rh_state != EHCI_RH_RUNNING && ehci->async_unlink)
+	if (ehci->rh_state < EHCI_RH_RUNNING && ehci->async_unlink)
 		end_unlink_async(ehci);
 
 	/* If the QH isn't linked then there's nothing we can do
@@ -1148,7 +1147,7 @@ ehci_endpoint_disable (struct usb_hcd *hcd, struct usb_host_endpoint *ep)
 		goto idle_timeout;
 	}
 
-	if (ehci->rh_state != EHCI_RH_RUNNING)
+	if (ehci->rh_state < EHCI_RH_RUNNING)
 		qh->qh_state = QH_STATE_IDLE;
 	switch (qh->qh_state) {
 	case QH_STATE_LINKED:

drivers/usb/host/ehci-hub.c

@@ -227,8 +227,7 @@ static int ehci_bus_suspend (struct usb_hcd *hcd)
 	}
 
 	/* stop schedules, clean any completed work */
-	if (ehci->rh_state == EHCI_RH_RUNNING)
-		ehci_quiesce (ehci);
+	ehci_quiesce(ehci);
 	ehci_work(ehci);
 
 	/* Unlike other USB host controller types, EHCI doesn't have

drivers/usb/host/ehci-q.c

@@ -433,15 +433,15 @@ qh_completions (struct ehci_hcd *ehci, struct ehci_qh *qh)
 
 		/* stop scanning when we reach qtds the hc is using */
 		} else if (likely (!stopped
-				&& ehci->rh_state == EHCI_RH_RUNNING)) {
+				&& ehci->rh_state >= EHCI_RH_RUNNING)) {
 			break;
 
 		/* scan the whole queue for unlinks whenever it stops */
 		} else {
 			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;
 
 			/* this qtd is active; skip it unless a previous qtd
@@ -1241,7 +1241,7 @@ static void start_unlink_async (struct ehci_hcd *ehci, struct ehci_qh *qh)
 	wmb ();
 
 	/* If the controller isn't running, we don't have to wait for it */
-	if (unlikely(ehci->rh_state != EHCI_RH_RUNNING)) {
+	if (unlikely(ehci->rh_state < EHCI_RH_RUNNING)) {
 		/* if (unlikely (qh->unlink_next != 0))
 		 *	this will recurse, probably not much
 		 */
@@ -1263,7 +1263,7 @@ static void scan_async (struct ehci_hcd *ehci)
 	enum ehci_timer_action	action = TIMER_IO_WATCHDOG;
 
 	timer_action_done (ehci, TIMER_ASYNC_SHRINK);
-	stopped = (ehci->rh_state != EHCI_RH_RUNNING);
+	stopped = (ehci->rh_state < EHCI_RH_RUNNING);
 
 	ehci->qh_scan_next = ehci->async->qh_next.qh;
 	while (ehci->qh_scan_next) {

drivers/usb/host/ehci-sched.c

@@ -2299,7 +2299,7 @@ scan_periodic (struct ehci_hcd *ehci)
 	 * Touches as few pages as possible:  cache-friendly.
 	 */
 	now_uframe = ehci->next_uframe;
-	if (ehci->rh_state == EHCI_RH_RUNNING) {
+	if (ehci->rh_state >= EHCI_RH_RUNNING) {
 		clock = ehci_read_frame_index(ehci);
 		clock_frame = (clock >> 3) & (ehci->periodic_size - 1);
 	} else  {
@@ -2334,7 +2334,7 @@ scan_periodic (struct ehci_hcd *ehci)
 			union ehci_shadow	temp;
 			int			live;
 
-			live = (ehci->rh_state == EHCI_RH_RUNNING);
+			live = (ehci->rh_state >= EHCI_RH_RUNNING);
 			switch (hc32_to_cpu(ehci, type)) {
 			case Q_TYPE_QH:
 				/* handle any completions */
@@ -2459,7 +2459,7 @@ scan_periodic (struct ehci_hcd *ehci)
 		 * We can't advance our scan without collecting the ISO
 		 * transfers that are still pending in this frame.
 		 */
-		if (incomplete && ehci->rh_state == EHCI_RH_RUNNING) {
+		if (incomplete && ehci->rh_state >= EHCI_RH_RUNNING) {
 			ehci->next_uframe = now_uframe;
 			break;
 		}
@@ -2475,7 +2475,7 @@ scan_periodic (struct ehci_hcd *ehci)
 		if (now_uframe == clock) {
 			unsigned	now;
 
-			if (ehci->rh_state != EHCI_RH_RUNNING
+			if (ehci->rh_state < EHCI_RH_RUNNING
 					|| ehci->periodic_sched == 0)
 				break;
 			ehci->next_uframe = now_uframe;

drivers/usb/host/ehci.h

@@ -62,10 +62,15 @@ struct ehci_stats {
 
 #define	EHCI_MAX_ROOT_PORTS	15		/* see HCS_N_PORTS */
 
+/*
+ * ehci_rh_state values of EHCI_RH_RUNNING or above mean that the
+ * controller may be doing DMA.  Lower values mean there's no DMA.
+ */
 enum ehci_rh_state {
 	EHCI_RH_HALTED,
 	EHCI_RH_SUSPENDED,
-	EHCI_RH_RUNNING
+	EHCI_RH_RUNNING,
+	EHCI_RH_STOPPING
 };
 
 struct ehci_hcd {			/* one per controller */