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>

22 files changed, 31 insertions, 70 deletions

diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index e68fef5361d2..bf10e9c4195e 100644
--- a/drivers/usb/core/hcd.c
+++ b/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);
-}
-
 
 /*-------------------------------------------------------------------------*/
 
diff --git a/drivers/usb/core/hcd.h b/drivers/usb/core/hcd.h
index 3ba258eb05de..1e4b81e9eb50 100644
--- a/drivers/usb/core/hcd.h
+++ b/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);
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 1e23e360ea91..5a338a5d4fe7 100644
--- a/drivers/usb/core/hub.c
+++ b/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;
diff --git a/drivers/usb/host/ohci-at91.c b/drivers/usb/host/ohci-at91.c
index e534f9de0f05..c96db1153dcf 100644
--- a/drivers/usb/host/ohci-at91.c
+++ b/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,
diff --git a/drivers/usb/host/ohci-au1xxx.c b/drivers/usb/host/ohci-au1xxx.c
index f90fe0c7373f..1b9abdba920b 100644
--- a/drivers/usb/host/ohci-au1xxx.c
+++ b/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,
diff --git a/drivers/usb/host/ohci-ep93xx.c b/drivers/usb/host/ohci-ep93xx.c
index 5adaf36e47d0..06aadfb0ec29 100644
--- a/drivers/usb/host/ohci-ep93xx.c
+++ b/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,
diff --git a/drivers/usb/host/ohci-hub.c b/drivers/usb/host/ohci-hub.c
index 355a82f25274..5be3bb3e6a9d 100644
--- a/drivers/usb/host/ohci-hub.c
+++ b/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 */
diff --git a/drivers/usb/host/ohci-lh7a404.c b/drivers/usb/host/ohci-lh7a404.c
index 13c12ed22252..96d14fa1d833 100644
--- a/drivers/usb/host/ohci-lh7a404.c
+++ b/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,
diff --git a/drivers/usb/host/ohci-omap.c b/drivers/usb/host/ohci-omap.c
index 3a7c24c03671..6859fb5f1d6f 100644
--- a/drivers/usb/host/ohci-omap.c
+++ b/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,
diff --git a/drivers/usb/host/ohci-pci.c b/drivers/usb/host/ohci-pci.c
index 4696cc912e16..3bf175d95a23 100644
--- a/drivers/usb/host/ohci-pci.c
+++ b/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,
diff --git a/drivers/usb/host/ohci-pnx4008.c b/drivers/usb/host/ohci-pnx4008.c
index 28b458f20cc3..664f07ee8732 100644
--- a/drivers/usb/host/ohci-pnx4008.c
+++ b/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,
diff --git a/drivers/usb/host/ohci-pnx8550.c b/drivers/usb/host/ohci-pnx8550.c
index 605d59cba28e..28467e288a93 100644
--- a/drivers/usb/host/ohci-pnx8550.c
+++ b/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,
diff --git a/drivers/usb/host/ohci-ppc-of.c b/drivers/usb/host/ohci-ppc-of.c
index a67252791223..50e55db13636 100644
--- a/drivers/usb/host/ohci-ppc-of.c
+++ b/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,
diff --git a/drivers/usb/host/ohci-ppc-soc.c b/drivers/usb/host/ohci-ppc-soc.c
index 523c30125577..cd3398b675b2 100644
--- a/drivers/usb/host/ohci-ppc-soc.c
+++ b/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,
diff --git a/drivers/usb/host/ohci-ps3.c b/drivers/usb/host/ohci-ps3.c
index c1935ae537f8..bfdeb0d22d05 100644
--- a/drivers/usb/host/ohci-ps3.c
+++ b/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,
diff --git a/drivers/usb/host/ohci-pxa27x.c b/drivers/usb/host/ohci-pxa27x.c
index d4ee27d92be8..70b0d4b459e7 100644
--- a/drivers/usb/host/ohci-pxa27x.c
+++ b/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,
diff --git a/drivers/usb/host/ohci-s3c2410.c b/drivers/usb/host/ohci-s3c2410.c
index ead4772f0f27..a73d2ff322e2 100644
--- a/drivers/usb/host/ohci-s3c2410.c
+++ b/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,
diff --git a/drivers/usb/host/ohci-sa1111.c b/drivers/usb/host/ohci-sa1111.c
index 0f48f2d99226..99438c65981b 100644
--- a/drivers/usb/host/ohci-sa1111.c
+++ b/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,
diff --git a/drivers/usb/host/ohci-sh.c b/drivers/usb/host/ohci-sh.c
index e7ee607278fe..60f03cc7ec4f 100644
--- a/drivers/usb/host/ohci-sh.c
+++ b/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,
diff --git a/drivers/usb/host/ohci-sm501.c b/drivers/usb/host/ohci-sm501.c
index 4a11e1816017..77204f001b9a 100644
--- a/drivers/usb/host/ohci-sm501.c
+++ b/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,
diff --git a/drivers/usb/host/ohci-ssb.c b/drivers/usb/host/ohci-ssb.c
index 7275186db315..c4265caec780 100644
--- a/drivers/usb/host/ohci-ssb.c
+++ b/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,
diff --git a/drivers/usb/host/u132-hcd.c b/drivers/usb/host/u132-hcd.c
index 9b6323f768b2..f29307405bb3 100644
--- a/drivers/usb/host/u132-hcd.c
+++ b/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,
 };
 
 /*