USB: don't explicitly reenable root-hub status interrupts

This patch (as1069b) changes the way OHCI root-hub status-change
interrupts are enabled.  Currently a special HCD method,
hub_irq_enable(), is called when the hub driver is finished using a
root hub.  This approach turns out to be subject to races, resulting
in unnecessary polling.

The patch does away with the method entirely.  Instead, the driver
automatically enables the RHSC interrupt when no more status changes
are present.  This scheme is safe with controllers using
level-triggered semantics for their interrupt flags.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/core/hcd.c

@@ -924,15 +924,6 @@ static int register_root_hub(struct usb_hcd *hcd)
 	return retval;
 }
 
-void usb_enable_root_hub_irq (struct usb_bus *bus)
-{
-	struct usb_hcd *hcd;
-
-	hcd = container_of (bus, struct usb_hcd, self);
-	if (hcd->driver->hub_irq_enable && hcd->state != HC_STATE_HALT)
-		hcd->driver->hub_irq_enable (hcd);
-}
-
 
 /*-------------------------------------------------------------------------*/
 

drivers/usb/core/hcd.h

@@ -210,8 +210,6 @@ struct hc_driver {
 	int	(*bus_suspend)(struct usb_hcd *);
 	int	(*bus_resume)(struct usb_hcd *);
 	int	(*start_port_reset)(struct usb_hcd *, unsigned port_num);
-	void	(*hub_irq_enable)(struct usb_hcd *);
-		/* Needed only if port-change IRQs are level-triggered */
 
 		/* force handover of high-speed port to full-speed companion */
 	void	(*relinquish_port)(struct usb_hcd *, int);

drivers/usb/core/hub.c

@@ -2001,8 +2001,6 @@ int usb_port_resume(struct usb_device *udev)
 	}
 
 	clear_bit(port1, hub->busy_bits);
-	if (!hub->hdev->parent && !hub->busy_bits[0])
-		usb_enable_root_hub_irq(hub->hdev->bus);
 
 	if (status == 0)
 		status = finish_port_resume(udev);
@@ -2918,11 +2916,6 @@ static void hub_events(void)
 
 		hub->activating = 0;
 
-		/* If this is a root hub, tell the HCD it's okay to
-		 * re-enable port-change interrupts now. */
-		if (!hdev->parent && !hub->busy_bits[0])
-			usb_enable_root_hub_irq(hdev->bus);
-
 loop_autopm:
 		/* Allow autosuspend if we're not going to run again */
 		if (list_empty(&hub->event_list))
@@ -3148,8 +3141,6 @@ int usb_reset_device(struct usb_device *udev)
 			break;
 	}
 	clear_bit(port1, parent_hub->busy_bits);
-	if (!parent_hdev->parent && !parent_hub->busy_bits[0])
-		usb_enable_root_hub_irq(parent_hdev->bus);
 
 	if (ret < 0)
 		goto re_enumerate;

drivers/usb/host/ohci-at91.c

@@ -261,7 +261,6 @@ static const struct hc_driver ohci_at91_hc_driver = {
 	 */
 	.hub_status_data =	ohci_hub_status_data,
 	.hub_control =		ohci_hub_control,
-	.hub_irq_enable =	ohci_rhsc_enable,
 #ifdef CONFIG_PM
 	.bus_suspend =		ohci_bus_suspend,
 	.bus_resume =		ohci_bus_resume,

drivers/usb/host/ohci-au1xxx.c

@@ -288,7 +288,6 @@ static const struct hc_driver ohci_au1xxx_hc_driver = {
 	 */
 	.hub_status_data =	ohci_hub_status_data,
 	.hub_control =		ohci_hub_control,
-	.hub_irq_enable =	ohci_rhsc_enable,
 #ifdef	CONFIG_PM
 	.bus_suspend =		ohci_bus_suspend,
 	.bus_resume =		ohci_bus_resume,

drivers/usb/host/ohci-ep93xx.c

@@ -135,7 +135,6 @@ static struct hc_driver ohci_ep93xx_hc_driver = {
 	.get_frame_number	= ohci_get_frame,
 	.hub_status_data	= ohci_hub_status_data,
 	.hub_control		= ohci_hub_control,
-	.hub_irq_enable		= ohci_rhsc_enable,
 #ifdef CONFIG_PM
 	.bus_suspend		= ohci_bus_suspend,
 	.bus_resume		= ohci_bus_resume,

drivers/usb/host/ohci-hub.c

@@ -36,18 +36,6 @@
 
 /*-------------------------------------------------------------------------*/
 
-/* hcd->hub_irq_enable() */
-static void ohci_rhsc_enable (struct usb_hcd *hcd)
-{
-	struct ohci_hcd		*ohci = hcd_to_ohci (hcd);
-
-	spin_lock_irq(&ohci->lock);
-	if (!ohci->autostop)
-		del_timer(&hcd->rh_timer);	/* Prevent next poll */
-	ohci_writel(ohci, OHCI_INTR_RHSC, &ohci->regs->intrenable);
-	spin_unlock_irq(&ohci->lock);
-}
-
 #define OHCI_SCHED_ENABLES \
 	(OHCI_CTRL_CLE|OHCI_CTRL_BLE|OHCI_CTRL_PLE|OHCI_CTRL_IE)
 
@@ -374,18 +362,28 @@ static int ohci_root_hub_state_changes(struct ohci_hcd *ohci, int changed,
 		int any_connected)
 {
 	int	poll_rh = 1;
+	int	rhsc;
 
+	rhsc = ohci_readl(ohci, &ohci->regs->intrenable) & OHCI_INTR_RHSC;
 	switch (ohci->hc_control & OHCI_CTRL_HCFS) {
 
 	case OHCI_USB_OPER:
-		/* keep on polling until we know a device is connected
-		 * and RHSC is enabled */
+		/* If no status changes are pending, enable status-change
+		 * interrupts.
+		 */
+		if (!rhsc && !changed) {
+			rhsc = OHCI_INTR_RHSC;
+			ohci_writel(ohci, rhsc, &ohci->regs->intrenable);
+		}
+
+		/* Keep on polling until we know a device is connected
+		 * and RHSC is enabled, or until we autostop.
+		 */
 		if (!ohci->autostop) {
 			if (any_connected ||
 					!device_may_wakeup(&ohci_to_hcd(ohci)
 						->self.root_hub->dev)) {
-				if (ohci_readl(ohci, &ohci->regs->intrenable) &
-						OHCI_INTR_RHSC)
+				if (rhsc)
 					poll_rh = 0;
 			} else {
 				ohci->autostop = 1;
@@ -398,12 +396,13 @@ static int ohci_root_hub_state_changes(struct ohci_hcd *ohci, int changed,
 				ohci->autostop = 0;
 				ohci->next_statechange = jiffies +
 						STATECHANGE_DELAY;
-			} else if (time_after_eq(jiffies,
+			} else if (rhsc && time_after_eq(jiffies,
 						ohci->next_statechange)
 					&& !ohci->ed_rm_list
 					&& !(ohci->hc_control &
 						OHCI_SCHED_ENABLES)) {
 				ohci_rh_suspend(ohci, 1);
+				poll_rh = 0;
 			}
 		}
 		break;
@@ -417,6 +416,12 @@ static int ohci_root_hub_state_changes(struct ohci_hcd *ohci, int changed,
 			else
 				usb_hcd_resume_root_hub(ohci_to_hcd(ohci));
 		} else {
+			if (!rhsc && (ohci->autostop ||
+					ohci_to_hcd(ohci)->self.root_hub->
+						do_remote_wakeup))
+				ohci_writel(ohci, OHCI_INTR_RHSC,
+						&ohci->regs->intrenable);
+
 			/* everything is idle, no need for polling */
 			poll_rh = 0;
 		}
@@ -438,12 +443,16 @@ static inline int ohci_rh_resume(struct ohci_hcd *ohci)
 static int ohci_root_hub_state_changes(struct ohci_hcd *ohci, int changed,
 		int any_connected)
 {
-	int	poll_rh = 1;
-
-	/* keep on polling until RHSC is enabled */
+	/* If RHSC is enabled, don't poll */
 	if (ohci_readl(ohci, &ohci->regs->intrenable) & OHCI_INTR_RHSC)
-		poll_rh = 0;
-	return poll_rh;
+		return 0;
+
+	/* If no status changes are pending, enable status-change interrupts */
+	if (!changed) {
+		ohci_writel(ohci, OHCI_INTR_RHSC, &ohci->regs->intrenable);
+		return 0;
+	}
+	return 1;
 }
 
 #endif	/* CONFIG_PM */

drivers/usb/host/ohci-lh7a404.c

@@ -193,7 +193,6 @@ static const struct hc_driver ohci_lh7a404_hc_driver = {
 	 */
 	.hub_status_data =	ohci_hub_status_data,
 	.hub_control =		ohci_hub_control,
-	.hub_irq_enable =	ohci_rhsc_enable,
 #ifdef	CONFIG_PM
 	.bus_suspend =		ohci_bus_suspend,
 	.bus_resume =		ohci_bus_resume,

drivers/usb/host/ohci-omap.c

@@ -466,7 +466,6 @@ static const struct hc_driver ohci_omap_hc_driver = {
 	 */
 	.hub_status_data =	ohci_hub_status_data,
 	.hub_control =		ohci_hub_control,
-	.hub_irq_enable =	ohci_rhsc_enable,
 #ifdef	CONFIG_PM
 	.bus_suspend =		ohci_bus_suspend,
 	.bus_resume =		ohci_bus_resume,

drivers/usb/host/ohci-pci.c

@@ -327,7 +327,6 @@ static const struct hc_driver ohci_pci_hc_driver = {
 	 */
 	.hub_status_data =	ohci_hub_status_data,
 	.hub_control =		ohci_hub_control,
-	.hub_irq_enable =	ohci_rhsc_enable,
 #ifdef	CONFIG_PM
 	.bus_suspend =		ohci_bus_suspend,
 	.bus_resume =		ohci_bus_resume,

drivers/usb/host/ohci-pnx4008.c

@@ -280,7 +280,6 @@ static const struct hc_driver ohci_pnx4008_hc_driver = {
 	 */
 	.hub_status_data = ohci_hub_status_data,
 	.hub_control = ohci_hub_control,
-	.hub_irq_enable = ohci_rhsc_enable,
 #ifdef	CONFIG_PM
 	.bus_suspend = ohci_bus_suspend,
 	.bus_resume = ohci_bus_resume,

drivers/usb/host/ohci-pnx8550.c

@@ -201,7 +201,6 @@ static const struct hc_driver ohci_pnx8550_hc_driver = {
 	 */
 	.hub_status_data =	ohci_hub_status_data,
 	.hub_control =		ohci_hub_control,
-	.hub_irq_enable =	ohci_rhsc_enable,
 #ifdef	CONFIG_PM
 	.bus_suspend =		ohci_bus_suspend,
 	.bus_resume =		ohci_bus_resume,

drivers/usb/host/ohci-ppc-of.c

@@ -72,7 +72,6 @@ static const struct hc_driver ohci_ppc_of_hc_driver = {
 	 */
 	.hub_status_data =	ohci_hub_status_data,
 	.hub_control =		ohci_hub_control,
-	.hub_irq_enable =	ohci_rhsc_enable,
 #ifdef	CONFIG_PM
 	.bus_suspend =		ohci_bus_suspend,
 	.bus_resume =		ohci_bus_resume,

drivers/usb/host/ohci-ppc-soc.c

@@ -172,7 +172,6 @@ static const struct hc_driver ohci_ppc_soc_hc_driver = {
 	 */
 	.hub_status_data =	ohci_hub_status_data,
 	.hub_control =		ohci_hub_control,
-	.hub_irq_enable =	ohci_rhsc_enable,
 #ifdef	CONFIG_PM
 	.bus_suspend =		ohci_bus_suspend,
 	.bus_resume =		ohci_bus_resume,

drivers/usb/host/ohci-ps3.c

@@ -68,7 +68,6 @@ static const struct hc_driver ps3_ohci_hc_driver = {
 	.get_frame_number	= ohci_get_frame,
 	.hub_status_data	= ohci_hub_status_data,
 	.hub_control		= ohci_hub_control,
-	.hub_irq_enable		= ohci_rhsc_enable,
 	.start_port_reset	= ohci_start_port_reset,
 #if defined(CONFIG_PM)
 	.bus_suspend 		= ohci_bus_suspend,

drivers/usb/host/ohci-pxa27x.c

@@ -298,7 +298,6 @@ static const struct hc_driver ohci_pxa27x_hc_driver = {
 	 */
 	.hub_status_data =	ohci_hub_status_data,
 	.hub_control =		ohci_hub_control,
-	.hub_irq_enable =	ohci_rhsc_enable,
 #ifdef  CONFIG_PM
 	.bus_suspend =		ohci_bus_suspend,
 	.bus_resume =		ohci_bus_resume,

drivers/usb/host/ohci-s3c2410.c

@@ -466,7 +466,6 @@ static const struct hc_driver ohci_s3c2410_hc_driver = {
 	 */
 	.hub_status_data =	ohci_s3c2410_hub_status_data,
 	.hub_control =		ohci_s3c2410_hub_control,
-	.hub_irq_enable =	ohci_rhsc_enable,
 #ifdef	CONFIG_PM
 	.bus_suspend =		ohci_bus_suspend,
 	.bus_resume =		ohci_bus_resume,

drivers/usb/host/ohci-sa1111.c

@@ -231,7 +231,6 @@ static const struct hc_driver ohci_sa1111_hc_driver = {
 	 */
 	.hub_status_data =	ohci_hub_status_data,
 	.hub_control =		ohci_hub_control,
-	.hub_irq_enable =	ohci_rhsc_enable,
 #ifdef	CONFIG_PM
 	.bus_suspend =		ohci_bus_suspend,
 	.bus_resume =		ohci_bus_resume,

drivers/usb/host/ohci-sh.c

@@ -68,7 +68,6 @@ static const struct hc_driver ohci_sh_hc_driver = {
 	 */
 	.hub_status_data =	ohci_hub_status_data,
 	.hub_control =		ohci_hub_control,
-	.hub_irq_enable =	ohci_rhsc_enable,
 #ifdef	CONFIG_PM
 	.bus_suspend =		ohci_bus_suspend,
 	.bus_resume =		ohci_bus_resume,

drivers/usb/host/ohci-sm501.c

@@ -75,7 +75,6 @@ static const struct hc_driver ohci_sm501_hc_driver = {
 	 */
 	.hub_status_data =	ohci_hub_status_data,
 	.hub_control =		ohci_hub_control,
-	.hub_irq_enable =	ohci_rhsc_enable,
 #ifdef	CONFIG_PM
 	.bus_suspend =		ohci_bus_suspend,
 	.bus_resume =		ohci_bus_resume,

drivers/usb/host/ohci-ssb.c

@@ -81,7 +81,6 @@ static const struct hc_driver ssb_ohci_hc_driver = {
 
 	.hub_status_data	= ohci_hub_status_data,
 	.hub_control		= ohci_hub_control,
-	.hub_irq_enable		= ohci_rhsc_enable,
 #ifdef	CONFIG_PM
 	.bus_suspend		= ohci_bus_suspend,
 	.bus_resume		= ohci_bus_resume,

drivers/usb/host/u132-hcd.c

@@ -2934,16 +2934,6 @@ static int u132_start_port_reset(struct usb_hcd *hcd, unsigned port_num)
 		return 0;
 }
 
-static void u132_hub_irq_enable(struct usb_hcd *hcd)
-{
-	struct u132 *u132 = hcd_to_u132(hcd);
-	if (u132->going > 1) {
-		dev_err(&u132->platform_dev->dev, "device has been removed %d\n"
-			, u132->going);
-	} else if (u132->going > 0)
-		dev_err(&u132->platform_dev->dev, "device is being removed\n");
-}
-
 
 #ifdef CONFIG_PM
 static int u132_bus_suspend(struct usb_hcd *hcd)
@@ -2995,7 +2985,6 @@ static struct hc_driver u132_hc_driver = {
 	.bus_suspend = u132_bus_suspend,
 	.bus_resume = u132_bus_resume,
 	.start_port_reset = u132_start_port_reset,
-	.hub_irq_enable = u132_hub_irq_enable,
 };
 
 /*