USB: separate root and non-root suspend/resume

This patch (as916) completes the separation of code paths for suspend
and resume of root hubs as opposed to non-root devices. Root hubs
will be power-managed through their bus_suspend and bus_resume
methods, whereas normal devices will use usb_port_suspend() and
usb_port_resume().

Changes to the hcd_bus_{suspend,resume} routines mostly represent
motion of code that was already present elsewhere. They include:

Adding debugging log messages,

Setting the device state appropriately, and

Adding a resume recovery time delay.

Changes to the port-suspend and port-resume routines in hub.c include:

Removal of checks for root devices (since they will never
be triggered), and

Removal of checks for NULL or invalid device pointers (these
were left over from earlier kernel versions and aren't needed
at all).

Signed-off-by: Alan Stern <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/core/generic.c

···
 {
 	int rc;
 
-	rc = usb_port_suspend(udev);
-
-	/* Root hubs don't have upstream ports to suspend,
-	 * so the line above won't do much for them.  We have to
-	 * shut down their downstream HC-to-USB interfaces manually,
-	 * by doing a bus (or "global") suspend.
+	/* Normal USB devices suspend through their upstream port.
+	 * Root hubs don't have upstream ports to suspend,
+	 * so we have to shut down their downstream HC-to-USB
+	 * interfaces manually by doing a bus (or "global") suspend.
 	 */
-	if (rc == 0 && !udev->parent) {
-		rc = hcd_bus_suspend(udev->bus);
-		if (rc) {
-			dev_dbg(&udev->dev, "'global' suspend %d\n", rc);
-			usb_port_resume(udev);
-		}
-	}
+	if (!udev->parent)
+		rc = hcd_bus_suspend(udev);
+	else
+		rc = usb_port_suspend(udev);
 	return rc;
 }
 
···
 {
 	int rc;
 
-	if (udev->reset_resume)
+	/* Normal USB devices resume/reset through their upstream port.
+	 * Root hubs don't have upstream ports to resume or reset,
+	 * so we have to start up their downstream HC-to-USB
+	 * interfaces manually by doing a bus (or "global") resume.
+	 */
+	if (!udev->parent)
+		rc = hcd_bus_resume(udev);
+	else if (udev->reset_resume)
 		rc = usb_reset_suspended_device(udev);
 	else
 		rc = usb_port_resume(udev);
-
-	/* Root hubs don't have upstream ports to resume or reset,
-	 * so the line above won't do much for them.  We have to
-	 * start up their downstream HC-to-USB interfaces manually,
-	 * by doing a bus (or "global") resume.
-	 */
-	if (rc == 0 && !udev->parent) {
-		rc = hcd_bus_resume(udev->bus);
-		if (rc)
-			dev_dbg(&udev->dev, "'global' resume %d\n", rc);
-		else {
-			/* TRSMRCY = 10 msec */
-			msleep(10);
-		}
-	}
 	return rc;
 }
 

drivers/usb/core/hcd.c

···
 
 #ifdef	CONFIG_PM
 
-int hcd_bus_suspend (struct usb_bus *bus)
+int hcd_bus_suspend(struct usb_device *rhdev)
 {
-	struct usb_hcd		*hcd;
-	int			status;
+	struct usb_hcd	*hcd = container_of(rhdev->bus, struct usb_hcd, self);
+	int		status;
+	int		old_state = hcd->state;
 
-	hcd = container_of (bus, struct usb_hcd, self);
-	if (!hcd->driver->bus_suspend)
-		return -ENOENT;
-	hcd->state = HC_STATE_QUIESCING;
-	status = hcd->driver->bus_suspend (hcd);
-	if (status == 0)
+	dev_dbg(&rhdev->dev, "bus %s%s\n",
+			rhdev->auto_pm ? "auto-" : "", "suspend");
+	if (!hcd->driver->bus_suspend) {
+		status = -ENOENT;
+	} else {
+		hcd->state = HC_STATE_QUIESCING;
+		status = hcd->driver->bus_suspend(hcd);
+	}
+	if (status == 0) {
+		usb_set_device_state(rhdev, USB_STATE_SUSPENDED);
 		hcd->state = HC_STATE_SUSPENDED;
-	else
-		dev_dbg(&bus->root_hub->dev, "%s fail, err %d\n",
+	} else {
+		hcd->state = old_state;
+		dev_dbg(&rhdev->dev, "bus %s fail, err %d\n",
 				"suspend", status);
+	}
 	return status;
 }
 
-int hcd_bus_resume (struct usb_bus *bus)
+int hcd_bus_resume(struct usb_device *rhdev)
 {
-	struct usb_hcd		*hcd;
-	int			status;
+	struct usb_hcd	*hcd = container_of(rhdev->bus, struct usb_hcd, self);
+	int		status;
 
-	hcd = container_of (bus, struct usb_hcd, self);
+	dev_dbg(&rhdev->dev, "usb %s%s\n",
+			rhdev->auto_pm ? "auto-" : "", "resume");
 	if (!hcd->driver->bus_resume)
 		return -ENOENT;
 	if (hcd->state == HC_STATE_RUNNING)
 		return 0;
+
 	hcd->state = HC_STATE_RESUMING;
-	status = hcd->driver->bus_resume (hcd);
-	if (status == 0)
+	status = hcd->driver->bus_resume(hcd);
+	if (status == 0) {
+		/* TRSMRCY = 10 msec */
+		msleep(10);
+		usb_set_device_state(rhdev, rhdev->actconfig
+				? USB_STATE_CONFIGURED
+				: USB_STATE_ADDRESS);
 		hcd->state = HC_STATE_RUNNING;
-	else {
-		dev_dbg(&bus->root_hub->dev, "%s fail, err %d\n",
+	} else {
+		dev_dbg(&rhdev->dev, "bus %s fail, err %d\n",
 				"resume", status);
 		usb_hc_died(hcd);
 	}

drivers/usb/core/hcd.h

···
 #ifdef CONFIG_PM
 extern void usb_hcd_resume_root_hub (struct usb_hcd *hcd);
 extern void usb_root_hub_lost_power (struct usb_device *rhdev);
-extern int hcd_bus_suspend (struct usb_bus *bus);
-extern int hcd_bus_resume (struct usb_bus *bus);
+extern int hcd_bus_suspend(struct usb_device *rhdev);
+extern int hcd_bus_resume(struct usb_device *rhdev);
 #else
 static inline void usb_hcd_resume_root_hub(struct usb_hcd *hcd)
 {
 	return;
-}
-
-static inline int hcd_bus_suspend(struct usb_bus *bus)
-{
-	return 0;
-}
-
-static inline int hcd_bus_resume (struct usb_bus *bus)
-{
-	return 0;
 }
 #endif /* CONFIG_PM */
 

drivers/usb/core/hub.c

···
 {
 	int	status = 0;
 
-	/* we change the device's upstream USB link,
-	 * but root hubs have no upstream USB link.
-	 */
-	if (udev->parent)
-		status = hub_port_suspend(hdev_to_hub(udev->parent),
-				udev->portnum, udev);
-	else {
-		dev_dbg(&udev->dev, "usb %ssuspend\n",
-				udev->auto_pm ? "auto-" : "");
-		usb_set_device_state(udev, USB_STATE_SUSPENDED);
-	}
+	status = hub_port_suspend(hdev_to_hub(udev->parent),
+			udev->portnum, udev);
 	return status;
 }
 
···
 			status);
 	else if (udev->actconfig) {
 		le16_to_cpus(&devstatus);
-		if ((devstatus & (1 << USB_DEVICE_REMOTE_WAKEUP))
-				&& udev->parent) {
+		if (devstatus & (1 << USB_DEVICE_REMOTE_WAKEUP)) {
 			status = usb_control_msg(udev,
 					usb_sndctrlpipe(udev, 0),
 					USB_REQ_CLEAR_FEATURE,
···
 					"wakeup, status %d\n", status);
 		}
 		status = 0;
-
-	} else if (udev->devnum <= 0) {
-		dev_dbg(&udev->dev, "bogus resume!\n");
-		status = -EINVAL;
 	}
 	return status;
 }
···
 			port1, status);
 	} else {
 		/* drive resume for at least 20 msec */
-		if (udev)
-			dev_dbg(&udev->dev, "usb %sresume\n",
-					udev->auto_pm ? "auto-" : "");
+		dev_dbg(&udev->dev, "usb %sresume\n",
+				udev->auto_pm ? "auto-" : "");
 		msleep(25);
 
 #define LIVE_FLAGS	( USB_PORT_STAT_POWER \
···
 						USB_PORT_FEAT_C_SUSPEND);
 			/* TRSMRCY = 10 msec */
 			msleep(10);
-			if (udev)
-				status = finish_port_resume(udev);
+			status = finish_port_resume(udev);
 		}
 	}
 	if (status < 0)
···
 {
 	int	status;
 
-	/* we change the device's upstream USB link,
-	 * but root hubs have no upstream USB link.
-	 */
-	if (udev->parent) {
-		// NOTE this fails if parent is also suspended...
-		status = hub_port_resume(hdev_to_hub(udev->parent),
-				udev->portnum, udev);
-	} else {
-		dev_dbg(&udev->dev, "usb %sresume\n",
-				udev->auto_pm ? "auto-" : "");
-		status = finish_port_resume(udev);
-	}
+	status = hub_port_resume(hdev_to_hub(udev->parent),
+			udev->portnum, udev);
 	if (status < 0)
 		dev_dbg(&udev->dev, "can't resume, status %d\n", status);
 	return status;