[PATCH] USB UHCI: Use root-hub IRQs while suspended

This patch, which has as478b as a prerequisite, enables the uhci-hcd
driver to take advantage of root-hub IRQs rather than polling during the
time it is suspended.  (Unfortunately the hardware doesn't support
port-change interrupts while the controller is running.)  It also turns
off the driver's private timer while the controller is suspended, as it
isn't needed then.  The combined elimination of polling interrupts and
timer interrupts ought to be enough to allow some systems to save a
noticeable amount of power while they are otherwise idle.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 60 insertions, 7 deletions

diff --git a/drivers/usb/host/uhci-hub.c b/drivers/usb/host/uhci-hub.c
index 13652de..4eace2b 100644
--- a/drivers/usb/host/uhci-hub.c
+++ b/drivers/usb/host/uhci-hub.c
@@ -49,22 +49,16 @@ static int any_ports_active(struct uhci_hcd *uhci)
 	return 0;
 }
 
-static int uhci_hub_status_data(struct usb_hcd *hcd, char *buf)
+static inline int get_hub_status_data(struct uhci_hcd *uhci, char *buf)
 {
-	struct uhci_hcd *uhci = hcd_to_uhci(hcd);
 	int port;
 
-	if (uhci->hc_inaccessible)
-		return 0;
-
 	*buf = 0;
 	for (port = 0; port < uhci->rh_numports; ++port) {
 		if ((inw(uhci->io_addr + USBPORTSC1 + port * 2) & RWC_BITS) ||
 				test_bit(port, &uhci->port_c_suspend))
 			*buf |= (1 << (port + 1));
 	}
-	if (*buf && uhci->is_stopped)
-		uhci->resume_detect = 1;
 	return !!*buf;
 }
 
@@ -134,6 +128,11 @@ static void uhci_check_ports(struct uhci_hcd *uhci)
 				set_bit(port, &uhci->resuming_ports);
 				uhci->ports_timeout = jiffies +
 						msecs_to_jiffies(20);
+
+				/* Make sure we see the port again
+				 * after the resuming period is over. */
+				mod_timer(&uhci_to_hcd(uhci)->rh_timer,
+						uhci->ports_timeout);
 			} else if (time_after_eq(jiffies,
 						uhci->ports_timeout)) {
 				uhci_finish_suspend(uhci, port, port_addr);
@@ -142,6 +141,60 @@ static void uhci_check_ports(struct uhci_hcd *uhci)
 	}
 }
 
+static int uhci_hub_status_data(struct usb_hcd *hcd, char *buf)
+{
+	struct uhci_hcd *uhci = hcd_to_uhci(hcd);
+	unsigned long flags;
+	int status;
+
+	spin_lock_irqsave(&uhci->lock, flags);
+	if (uhci->hc_inaccessible) {
+		status = 0;
+		goto done;
+	}
+
+	uhci_check_ports(uhci);
+	status = get_hub_status_data(uhci, buf);
+
+	switch (uhci->rh_state) {
+	    case UHCI_RH_SUSPENDING:
+	    case UHCI_RH_SUSPENDED:
+		/* if port change, ask to be resumed */
+		if (status)
+			usb_hcd_resume_root_hub(hcd);
+		break;
+
+	    case UHCI_RH_AUTO_STOPPED:
+		/* if port change, auto start */
+		if (status)
+			wakeup_rh(uhci);
+		break;
+
+	    case UHCI_RH_RUNNING:
+		/* are any devices attached? */
+		if (!any_ports_active(uhci)) {
+			uhci->rh_state = UHCI_RH_RUNNING_NODEVS;
+			uhci->auto_stop_time = jiffies + HZ;
+		}
+		break;
+
+	    case UHCI_RH_RUNNING_NODEVS:
+		/* auto-stop if nothing connected for 1 second */
+		if (any_ports_active(uhci))
+			uhci->rh_state = UHCI_RH_RUNNING;
+		else if (time_after_eq(jiffies, uhci->auto_stop_time))
+			suspend_rh(uhci, UHCI_RH_AUTO_STOPPED);
+		break;
+
+	    default:
+		break;
+	}
+
+done:
+	spin_unlock_irqrestore(&uhci->lock, flags);
+	return status;
+}
+
 /* size of returned buffer is part of USB spec */
 static int uhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
 			u16 wIndex, char *buf, u16 wLength)