USB: OHCI avoids root hub timer polling

This teaches OHCI to use the root hub status change (RHSC) IRQ, bypassing
root hub timers most of the time and switching over to the "new" root hub
polling scheme.  It's complicated by the fact that implementations of OHCI
trigger and ack that IRQ differently (the spec is vague there).

Avoiding root hub timers helps mechanisms like "dynamic tick" leave the
CPU in lowpower modes for longer intervals.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 4 insertions, 1 deletions

diff --git a/drivers/usb/host/ohci-pci.c b/drivers/usb/host/ohci-pci.c
index 37e122812b67..ef874443aa9f 100644
--- a/drivers/usb/host/ohci-pci.c
+++ b/drivers/usb/host/ohci-pci.c
@@ -176,11 +176,13 @@ static const struct hc_driver ohci_pci_hc_driver = {
          */
         .reset =                ohci_pci_reset,
         .start =                ohci_pci_start,
+        .stop =                 ohci_stop,
+
 #ifdef  CONFIG_PM
+        /* these suspend/resume entries are for upstream PCI glue ONLY */
         .suspend =              ohci_pci_suspend,
         .resume =               ohci_pci_resume,
 #endif
-        .stop =                 ohci_stop,
 
         /*
          * managing i/o requests and associated device resources
@@ -199,6 +201,7 @@ 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,