USB: automatically enable RHSC interrupts

This patch (as1069c) 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>

3 files changed, 0 insertions, 22 deletions

diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index f7bfd72ef11..8abd4e59bf4 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 5b0b59b0d89..e710ce04e22 100644
--- a/drivers/usb/core/hcd.h
+++ b/drivers/usb/core/hcd.h
@@ -212,8 +212,6 @@ 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);
@@ -379,8 +377,6 @@ extern struct list_head usb_bus_list;
 extern struct mutex usb_bus_list_lock;
 extern wait_queue_head_t usb_kill_urb_queue;
 
-extern void usb_enable_root_hub_irq(struct usb_bus *bus);
-
 extern int usb_find_interface_driver(struct usb_device *dev,
         struct usb_interface *interface);
 
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 107e1d25dde..6a5cb018383 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -2102,8 +2102,6 @@ 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);
 
         status = check_port_resume_type(udev,
                         hub, port1, status, portchange, portstatus);
@@ -3081,11 +3079,6 @@ static void hub_events(void)
                         }
                 }
 
-                /* 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))
@@ -3311,8 +3304,6 @@ static int usb_reset_and_verify_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;