[PATCH] usb_interface power state

This updates the handling of power state for USB interfaces.

  - Formalizes an existing invariant:  interface "power state" is a boolean:
    ON when I/O is allowed, and FREEZE otherwise.  It does so by defining
    some inlined helpers, then using them.

  - Adds a useful invariant:  the only interfaces marked active are those
    bound to non-suspended drivers.  Later patches build on this invariant.

  - Simplifies the interface driver API (and removes some error paths) by
    removing the requirement that they record power state changes during
    suspend and resume callbacks.  Now usbcore does that.

A few drivers were simplified to address that last change.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

 drivers/usb/core/hub.c       |   33 +++++++++------------
 drivers/usb/core/message.c   |    1
 drivers/usb/core/usb.c       |   65 +++++++++++++++++++++++++++++++++----------
 drivers/usb/core/usb.h       |   18 +++++++++++
 drivers/usb/input/hid-core.c |    2 -
 drivers/usb/misc/usbtest.c   |   10 ------
 drivers/usb/net/pegasus.c    |    2 -
 drivers/usb/net/usbnet.c     |    2 -
 8 files changed, 85 insertions(+), 48 deletions(-)

drivers/usb/core/hub.c

@@ -1624,7 +1624,7 @@ static int __usb_suspend_device (struct usb_device *udev, int port1,
 			struct usb_driver	*driver;
 
 			intf = udev->actconfig->interface[i];
-			if (state.event <= intf->dev.power.power_state.event)
+			if (!is_active(intf))
 				continue;
 			if (!intf->dev.driver)
 				continue;
@@ -1632,11 +1632,12 @@ static int __usb_suspend_device (struct usb_device *udev, int port1,
 
 			if (driver->suspend) {
 				status = driver->suspend(intf, state);
-				if (intf->dev.power.power_state.event != state.event
-						|| status)
+				if (status == 0)
+					mark_quiesced(intf);
+				else
 					dev_err(&intf->dev,
-						"suspend %d fail, code %d\n",
-						state.event, status);
+						"suspend error %d\n",
+						status);
 			}
 
 			/* only drivers with suspend() can ever resume();
@@ -1787,7 +1788,7 @@ static int finish_port_resume(struct usb_device *udev)
 			struct usb_driver	*driver;
 
 			intf = udev->actconfig->interface[i];
-			if (intf->dev.power.power_state.event == PM_EVENT_ON)
+			if (is_active(intf))
 				continue;
 			if (!intf->dev.driver) {
 				/* FIXME maybe force to alt 0 */
@@ -1800,12 +1801,14 @@ static int finish_port_resume(struct usb_device *udev)
 				continue;
 
 			/* can we do better than just logging errors? */
+			mark_active(intf);
 			status = driver->resume(intf);
-			if (intf->dev.power.power_state.event != PM_EVENT_ON
-					|| status)
+			if (status < 0) {
+				mark_quiesced(intf);
 				dev_dbg(&intf->dev,
-					"resume fail, state %d code %d\n",
-					intf->dev.power.power_state.event, status);
+					"resume error %d\n",
+					status);
+			}
 		}
 		status = 0;
 
@@ -1952,7 +1955,7 @@ static int remote_wakeup(struct usb_device *udev)
 	return status;
 }
 
-static int hub_suspend(struct usb_interface *intf, pm_message_t state)
+static int hub_suspend(struct usb_interface *intf, pm_message_t msg)
 {
 	struct usb_hub		*hub = usb_get_intfdata (intf);
 	struct usb_device	*hdev = hub->hdev;
@@ -1970,14 +1973,13 @@ static int hub_suspend(struct usb_interface *intf, pm_message_t state)
 		if (!udev)
 			continue;
 		down(&udev->serialize);
-		status = __usb_suspend_device(udev, port1, state);
+		status = __usb_suspend_device(udev, port1, msg);
 		up(&udev->serialize);
 		if (status < 0)
 			dev_dbg(&intf->dev, "suspend port %d --> %d\n",
 				port1, status);
 	}
 
-	intf->dev.power.power_state = state;
 	return 0;
 }
 
@@ -1988,9 +1990,6 @@ static int hub_resume(struct usb_interface *intf)
 	unsigned		port1;
 	int			status;
 
-	if (intf->dev.power.power_state.event == PM_EVENT_ON)
-		return 0;
-
 	for (port1 = 1; port1 <= hdev->maxchild; port1++) {
 		struct usb_device	*udev;
 		u16			portstat, portchange;
@@ -2024,8 +2023,6 @@ static int hub_resume(struct usb_interface *intf)
 		}
 		up(&udev->serialize);
 	}
-	intf->dev.power.power_state = PMSG_ON;
-
 	hub->resume_root_hub = 0;
 	hub_activate(hub);
 	return 0;

drivers/usb/core/message.c

@@ -1393,6 +1393,7 @@ free_interfaces:
 			intf->dev.dma_mask = dev->dev.dma_mask;
 			intf->dev.release = release_interface;
 			device_initialize (&intf->dev);
+			mark_quiesced(intf);
 			sprintf (&intf->dev.bus_id[0], "%d-%s:%d.%d",
 				 dev->bus->busnum, dev->devpath,
 				 configuration,

drivers/usb/core/usb.c

@@ -107,10 +107,19 @@ static int usb_probe_interface(struct device *dev)
 	id = usb_match_id (intf, driver->id_table);
 	if (id) {
 		dev_dbg (dev, "%s - got id\n", __FUNCTION__);
+
+		/* Interface "power state" doesn't correspond to any hardware
+		 * state whatsoever.  We use it to record when it's bound to
+		 * a driver that may start I/0:  it's not frozen/quiesced.
+		 */
+		mark_active(intf);
 		intf->condition = USB_INTERFACE_BINDING;
 		error = driver->probe (intf, id);
-		intf->condition = error ? USB_INTERFACE_UNBOUND :
-				USB_INTERFACE_BOUND;
+		if (error) {
+			mark_quiesced(intf);
+			intf->condition = USB_INTERFACE_UNBOUND;
+		} else
+			intf->condition = USB_INTERFACE_BOUND;
 	}
 
 	return error;
@@ -136,6 +145,7 @@ static int usb_unbind_interface(struct device *dev)
 			0);
 	usb_set_intfdata(intf, NULL);
 	intf->condition = USB_INTERFACE_UNBOUND;
+	mark_quiesced(intf);
 
 	return 0;
 }
@@ -299,6 +309,7 @@ int usb_driver_claim_interface(struct usb_driver *driver,
 	dev->driver = &driver->driver;
 	usb_set_intfdata(iface, priv);
 	iface->condition = USB_INTERFACE_BOUND;
+	mark_active(iface);
 
 	/* if interface was already added, bind now; else let
 	 * the future device_add() bind it, bypassing probe()
@@ -345,6 +356,7 @@ void usb_driver_release_interface(struct usb_driver *driver,
 	dev->driver = NULL;
 	usb_set_intfdata(iface, NULL);
 	iface->condition = USB_INTERFACE_UNBOUND;
+	mark_quiesced(iface);
 }
 
 /**
@@ -1404,8 +1416,9 @@ void usb_buffer_unmap_sg (struct usb_device *dev, unsigned pipe,
 
 static int usb_generic_suspend(struct device *dev, pm_message_t message)
 {
-	struct usb_interface *intf;
-	struct usb_driver *driver;
+	struct usb_interface	*intf;
+	struct usb_driver	*driver;
+	int			status;
 
 	if (dev->driver == &usb_generic_driver)
 		return usb_suspend_device (to_usb_device(dev), message);
@@ -1417,21 +1430,34 @@ static int usb_generic_suspend(struct device *dev, pm_message_t message)
 	intf = to_usb_interface(dev);
 	driver = to_usb_driver(dev->driver);
 
-	/* there's only one USB suspend state */
-	if (intf->dev.power.power_state.event)
+	/* with no hardware, USB interfaces only use FREEZE and ON states */
+	if (!is_active(intf))
 		return 0;
 
-	if (driver->suspend)
-		return driver->suspend(intf, message);
-	return 0;
+	if (driver->suspend && driver->resume) {
+		status = driver->suspend(intf, message);
+		if (status)
+			dev_err(dev, "%s error %d\n", "suspend", status);
+		else
+			mark_quiesced(intf);
+	} else {
+		// FIXME else if there's no suspend method, disconnect...
+		dev_warn(dev, "no %s?\n", "suspend");
+		status = 0;
+	}
+	return status;
 }
 
 static int usb_generic_resume(struct device *dev)
 {
-	struct usb_interface *intf;
-	struct usb_driver *driver;
+	struct usb_interface	*intf;
+	struct usb_driver	*driver;
+	int			status;
+
+	if (dev->power.power_state.event == PM_EVENT_ON)
+		return 0;
 
-	/* devices resume through their hub */
+	/* devices resume through their hubs */
 	if (dev->driver == &usb_generic_driver)
 		return usb_resume_device (to_usb_device(dev));
 
@@ -1442,8 +1468,19 @@ static int usb_generic_resume(struct device *dev)
 	intf = to_usb_interface(dev);
 	driver = to_usb_driver(dev->driver);
 
-	if (driver->resume)
-		return driver->resume(intf);
+	/* if driver was suspended, it has a resume method;
+	 * however, sysfs can wrongly mark things as suspended
+	 * (on the "no suspend method" FIXME path above)
+	 */
+	mark_active(intf);
+	if (driver->resume) {
+		status = driver->resume(intf);
+		if (status) {
+			dev_err(dev, "%s error %d\n", "resume", status);
+			mark_quiesced(intf);
+		}
+	} else
+		dev_warn(dev, "no %s?\n", "resume");
 	return 0;
 }
 

drivers/usb/core/usb.h

@@ -28,6 +28,24 @@ extern void usb_major_cleanup(void);
 extern int usb_host_init(void);
 extern void usb_host_cleanup(void);
 
+/* Interfaces and their "power state" are owned by usbcore */
+
+static inline void mark_active(struct usb_interface *f)
+{
+	f->dev.power.power_state.event = PM_EVENT_ON;
+}
+
+static inline void mark_quiesced(struct usb_interface *f)
+{
+	f->dev.power.power_state.event = PM_EVENT_FREEZE;
+}
+
+static inline int is_active(struct usb_interface *f)
+{
+	return f->dev.power.power_state.event == PM_EVENT_ON;
+}
+
+
 /* for labeling diagnostics */
 extern const char *usbcore_name;
 

drivers/usb/input/hid-core.c

@@ -1887,7 +1887,6 @@ static int hid_suspend(struct usb_interface *intf, pm_message_t message)
 	struct hid_device *hid = usb_get_intfdata (intf);
 
 	usb_kill_urb(hid->urbin);
-	intf->dev.power.power_state = PMSG_SUSPEND;
 	dev_dbg(&intf->dev, "suspend\n");
 	return 0;
 }
@@ -1897,7 +1896,6 @@ static int hid_resume(struct usb_interface *intf)
 	struct hid_device *hid = usb_get_intfdata (intf);
 	int status;
 
-	intf->dev.power.power_state = PMSG_ON;
 	if (hid->open)
 		status = usb_submit_urb(hid->urbin, GFP_NOIO);
 	else

drivers/usb/misc/usbtest.c

@@ -1948,21 +1948,11 @@ usbtest_probe (struct usb_interface *intf, const struct usb_device_id *id)
 
 static int usbtest_suspend (struct usb_interface *intf, pm_message_t message)
 {
-	struct usbtest_dev	*dev = usb_get_intfdata (intf);
-
-	down (&dev->sem);
-	intf->dev.power.power_state = PMSG_SUSPEND;
-	up (&dev->sem);
 	return 0;
 }
 
 static int usbtest_resume (struct usb_interface *intf)
 {
-	struct usbtest_dev	*dev = usb_get_intfdata (intf);
-
-	down (&dev->sem);
-	intf->dev.power.power_state = PMSG_ON;
-	up (&dev->sem);
 	return 0;
 }
 

drivers/usb/net/pegasus.c

@@ -1384,7 +1384,6 @@ static int pegasus_suspend (struct usb_interface *intf, pm_message_t message)
 		usb_kill_urb(pegasus->rx_urb);
 		usb_kill_urb(pegasus->intr_urb);
 	}
-	intf->dev.power.power_state = PMSG_SUSPEND;
 	return 0;
 }
 
@@ -1392,7 +1391,6 @@ static int pegasus_resume (struct usb_interface *intf)
 {
 	struct pegasus *pegasus = usb_get_intfdata(intf);
 
-	intf->dev.power.power_state = PMSG_ON;
 	netif_device_attach (pegasus->net);
 	if (netif_running(pegasus->net)) {
 		pegasus->rx_urb->status = 0;

drivers/usb/net/usbnet.c

@@ -1185,7 +1185,6 @@ int usbnet_suspend (struct usb_interface *intf, pm_message_t message)
 	netif_device_detach (dev->net);
 	(void) unlink_urbs (dev, &dev->rxq);
 	(void) unlink_urbs (dev, &dev->txq);
-	intf->dev.power.power_state = PMSG_SUSPEND;
 	return 0;
 }
 EXPORT_SYMBOL_GPL(usbnet_suspend);
@@ -1194,7 +1193,6 @@ int usbnet_resume (struct usb_interface *intf)
 {
 	struct usbnet		*dev = usb_get_intfdata(intf);
 
-	intf->dev.power.power_state = PMSG_ON;
 	netif_device_attach (dev->net);
 	tasklet_schedule (&dev->bh);
 	return 0;