OHCI: add auto-stop support

This patch (as790b) adds "autostop" support to ohci-hcd: the driver
will automatically stop the host controller when no devices have been
connected for at least one second.  This feature is useful when the
USB autosuspend facility isn't available, such as when
CONFIG_USB_SUSPEND hasn't been set.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/host/ohci-hcd.c

@@ -715,17 +715,8 @@ static irqreturn_t ohci_irq (struct usb_hcd *hcd, struct pt_regs *ptregs)
 		return IRQ_NOTMINE;
 	}
 
-	/* NOTE:  vendors didn't always make the same implementation
-	 * choices for RHSC.  Sometimes it triggers on an edge (like
-	 * setting and maybe clearing a port status change bit); and
-	 * it's level-triggered on other silicon, active until khubd
-	 * clears all active port status change bits.  Poll by timer
-	 * til it's fully debounced and the difference won't matter.
-	 */
 	if (ints & OHCI_INTR_RHSC) {
 		ohci_vdbg (ohci, "rhsc\n");
-		ohci_writel (ohci, OHCI_INTR_RHSC, &regs->intrdisable);
-		hcd->poll_rh = 1;
 		ohci->next_statechange = jiffies + STATECHANGE_DELAY;
 		ohci_writel (ohci, OHCI_INTR_RHSC, &regs->intrstatus);
 		usb_hcd_poll_rh_status(hcd);
@@ -743,7 +734,12 @@ static irqreturn_t ohci_irq (struct usb_hcd *hcd, struct pt_regs *ptregs)
 	if (ints & OHCI_INTR_RD) {
 		ohci_vdbg (ohci, "resume detect\n");
 		ohci_writel (ohci, OHCI_INTR_RD, &regs->intrstatus);
-		if (hcd->state != HC_STATE_QUIESCING)
+		hcd->poll_rh = 1;
+		if (ohci->autostop) {
+			spin_lock (&ohci->lock);
+			ohci_rh_resume (ohci);
+			spin_unlock (&ohci->lock);
+		} else
 			usb_hcd_resume_root_hub(hcd);
 	}
 

drivers/usb/host/ohci.h

@@ -388,6 +388,7 @@ struct ohci_hcd {
 	u32 			hc_control;	/* copy of hc control reg */
 	unsigned long		next_statechange;	/* suspend/resume */
 	u32			fminterval;		/* saved register */
+	unsigned		autostop:1;	/* rh auto stopping/stopped */
 
 	unsigned long		flags;		/* for HC bugs */
 #define	OHCI_QUIRK_AMD756	0x01			/* erratum #4 */