EHCI: keep track of ports being resumed and indicate in hub_status_data

This patch (as1537) adds a bit-array to ehci-hcd for keeping track of
which ports are undergoing a resume transition.  If any of the bits
are set when ehci_hub_status_data() is called, the routine will return
a nonzero value even if no ports have any status changes pending.
This will allow usbcore to handle races between root-hub suspend and
port wakeup.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: Sarah Sharp <sarah.a.sharp@linux.intel.com>
CC: Chen Peter-B29397 <B29397@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/ehci-hcd.c

@@ -347,6 +347,8 @@ static int ehci_reset (struct ehci_hcd *ehci)
 	if (ehci->debug)
 		dbgp_external_startup();
 
+	ehci->port_c_suspend = ehci->suspended_ports =
+			ehci->resuming_ports = 0;
 	return retval;
 }
 
@@ -939,6 +941,7 @@ static irqreturn_t ehci_irq (struct usb_hcd *hcd)
 			 * like usb_port_resume() does.
 			 */
 			ehci->reset_done[i] = jiffies + msecs_to_jiffies(25);
+			set_bit(i, &ehci->resuming_ports);
 			ehci_dbg (ehci, "port %d remote wakeup\n", i + 1);
 			mod_timer(&hcd->rh_timer, ehci->reset_done[i]);
 		}

drivers/usb/host/ehci-hub.c

@@ -223,17 +223,12 @@ static int ehci_bus_suspend (struct usb_hcd *hcd)
 	 * remote wakeup, we must fail the suspend.
 	 */
 	if (hcd->self.root_hub->do_remote_wakeup) {
-		port = HCS_N_PORTS(ehci->hcs_params);
-		while (port--) {
-			if (ehci->reset_done[port] != 0) {
+		if (ehci->resuming_ports) {
 			spin_unlock_irq(&ehci->lock);
-				ehci_dbg(ehci, "suspend failed because "
-						"port %d is resuming\n",
-						port + 1);
+			ehci_dbg(ehci, "suspend failed because a port is resuming\n");
 			return -EBUSY;
 		}
 	}
-	}
 
 	/* stop schedules, clean any completed work */
 	if (ehci->rh_state == EHCI_RH_RUNNING)
@@ -554,16 +549,12 @@ static int
 ehci_hub_status_data (struct usb_hcd *hcd, char *buf)
 {
 	struct ehci_hcd	*ehci = hcd_to_ehci (hcd);
-	u32		temp, status = 0;
+	u32		temp, status;
 	u32		mask;
 	int		ports, i, retval = 1;
 	unsigned long	flags;
 	u32		ppcd = 0;
 
-	/* if !USB_SUSPEND, root hub timers won't get shut down ... */
-	if (ehci->rh_state != EHCI_RH_RUNNING)
-		return 0;
-
 	/* init status to no-changes */
 	buf [0] = 0;
 	ports = HCS_N_PORTS (ehci->hcs_params);
@@ -572,6 +563,11 @@ ehci_hub_status_data (struct usb_hcd *hcd, char *buf)
 		retval++;
 	}
 
+	/* Inform the core about resumes-in-progress by returning
+	 * a non-zero value even if there are no status changes.
+	 */
+	status = ehci->resuming_ports;
+
 	/* Some boards (mostly VIA?) report bogus overcurrent indications,
 	 * causing massive log spam unless we completely ignore them.  It
 	 * may be relevant that VIA VT8235 controllers, where PORT_POWER is
@@ -846,6 +842,7 @@ static int ehci_hub_control (
 				ehci_writel(ehci,
 					temp & ~(PORT_RWC_BITS | PORT_RESUME),
 					status_reg);
+				clear_bit(wIndex, &ehci->resuming_ports);
 				retval = handshake(ehci, status_reg,
 					   PORT_RESUME, 0, 2000 /* 2msec */);
 				if (retval != 0) {
@@ -864,6 +861,7 @@ static int ehci_hub_control (
 					ehci->reset_done[wIndex])) {
 			status |= USB_PORT_STAT_C_RESET << 16;
 			ehci->reset_done [wIndex] = 0;
+			clear_bit(wIndex, &ehci->resuming_ports);
 
 			/* force reset to complete */
 			ehci_writel(ehci, temp & ~(PORT_RWC_BITS | PORT_RESET),
@@ -884,8 +882,10 @@ static int ehci_hub_control (
 					ehci_readl(ehci, status_reg));
 		}
 
-		if (!(temp & (PORT_RESUME|PORT_RESET)))
+		if (!(temp & (PORT_RESUME|PORT_RESET))) {
 			ehci->reset_done[wIndex] = 0;
+			clear_bit(wIndex, &ehci->resuming_ports);
+		}
 
 		/* transfer dedicated ports to the companion hc */
 		if ((temp & PORT_CONNECT) &&
@@ -920,6 +920,7 @@ static int ehci_hub_control (
 			status |= USB_PORT_STAT_SUSPEND;
 		} else if (test_bit(wIndex, &ehci->suspended_ports)) {
 			clear_bit(wIndex, &ehci->suspended_ports);
+			clear_bit(wIndex, &ehci->resuming_ports);
 			ehci->reset_done[wIndex] = 0;
 			if (temp & PORT_PE)
 				set_bit(wIndex, &ehci->port_c_suspend);

drivers/usb/host/ehci-tegra.c

@@ -224,6 +224,7 @@ static int tegra_ehci_hub_control(
 		temp &= ~(PORT_RWC_BITS | PORT_WAKE_BITS);
 		/* start resume signalling */
 		ehci_writel(ehci, temp | PORT_RESUME, status_reg);
+		set_bit(wIndex-1, &ehci->resuming_ports);
 
 		spin_unlock_irqrestore(&ehci->lock, flags);
 		msleep(20);
@@ -236,6 +237,7 @@ static int tegra_ehci_hub_control(
 			pr_err("%s: timeout waiting for SUSPEND\n", __func__);
 
 		ehci->reset_done[wIndex-1] = 0;
+		clear_bit(wIndex-1, &ehci->resuming_ports);
 
 		tegra->port_resuming = 1;
 		goto done;

drivers/usb/host/ehci.h

@@ -117,6 +117,8 @@ struct ehci_hcd {			/* one per controller */
 			the change-suspend feature turned on */
 	unsigned long		suspended_ports;	/* which ports are
 			suspended */
+	unsigned long		resuming_ports;		/* which ports have
+			started to resume */
 
 	/* per-HC memory pools (could be per-bus, but ...) */
 	struct dma_pool		*qh_pool;	/* qh per active urb */