USB: prepare for changover to Runtime PM framework

This patch (as1303) revises the USB Power Management infrastructure to
make it compatible with the new driver-model Runtime PM framework:

	Drivers are no longer allowed to access intf->pm_usage_cnt
	directly; the PM framework manages its own usage counters.

	usb_autopm_set_interface() is eliminated, because it directly
	sets intf->pm_usage_cnt.

	usb_autopm_enable() and usb_autopm_disable() are eliminated,
	because they call usb_autopm_set_interface().

	usb_autopm_get_interface_no_resume() and
	usb_autopm_put_interface_no_suspend() are added.  They
	correspond to pm_runtime_get_noresume() and
	pm_runtime_put_noidle() in the PM framework.

	The power/level attribute no longer accepts "suspend", only
	"on" and "auto".  The PM framework doesn't allow devices to be
	forced into a suspended mode.

The hub driver contains the only code that violates the new
guidelines.  It is updated to use the new interface routines instead.

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

Documentation/usb/power-management.txt

@@ -2,7 +2,7 @@
 
 		 Alan Stern <stern@rowland.harvard.edu>
 
-			    October 5, 2007
+			    November 10, 2009
 
 
 
@@ -123,9 +123,9 @@ relevant attribute files are: wakeup, level, and autosuspend.
 
 	power/level
 
-		This file contains one of three words: "on", "auto",
-		or "suspend".  You can write those words to the file
-		to change the device's setting.
+		This file contains one of two words: "on" or "auto".
+		You can write those words to the file to change the
+		device's setting.
 
 		"on" means that the device should be resumed and
 		autosuspend is not allowed.  (Of course, system
@@ -134,10 +134,10 @@ relevant attribute files are: wakeup, level, and autosuspend.
 		"auto" is the normal state in which the kernel is
 		allowed to autosuspend and autoresume the device.
 
-		"suspend" means that the device should remain
-		suspended, and autoresume is not allowed.  (But remote
-		wakeup may still be allowed, since it is controlled
-		separately by the power/wakeup attribute.)
+		(In kernels up to 2.6.32, you could also specify
+		"suspend", meaning that the device should remain
+		suspended and autoresume was not allowed.  This
+		setting is no longer supported.)
 
 	power/autosuspend
 
@@ -313,13 +313,14 @@ three of the methods listed above.  In addition, a driver indicates
 that it supports autosuspend by setting the .supports_autosuspend flag
 in its usb_driver structure.  It is then responsible for informing the
 USB core whenever one of its interfaces becomes busy or idle.  The
-driver does so by calling these five functions:
+driver does so by calling these six functions:
 
 	int  usb_autopm_get_interface(struct usb_interface *intf);
 	void usb_autopm_put_interface(struct usb_interface *intf);
-	int  usb_autopm_set_interface(struct usb_interface *intf);
 	int  usb_autopm_get_interface_async(struct usb_interface *intf);
 	void usb_autopm_put_interface_async(struct usb_interface *intf);
+	void usb_autopm_get_interface_no_resume(struct usb_interface *intf);
+	void usb_autopm_put_interface_no_suspend(struct usb_interface *intf);
 
 The functions work by maintaining a counter in the usb_interface
 structure.  When intf->pm_usage_count is > 0 then the interface is
@@ -331,11 +332,13 @@ considered to be idle, and the kernel may autosuspend the device.
 associated with the device itself rather than any of its interfaces.
 This field is used only by the USB core.)
 
-The driver owns intf->pm_usage_count; it can modify the value however
-and whenever it likes.  A nice aspect of the non-async usb_autopm_*
-routines is that the changes they make are protected by the usb_device
-structure's PM mutex (udev->pm_mutex); however drivers may change
-pm_usage_count without holding the mutex.  Drivers using the async
+Drivers must not modify intf->pm_usage_count directly; its value
+should be changed only be using the functions listed above.  Drivers
+are responsible for insuring that the overall change to pm_usage_count
+during their lifetime balances out to 0 (it may be necessary for the
+disconnect method to call usb_autopm_put_interface() one or more times
+to fulfill this requirement).  The first two routines use the PM mutex
+in struct usb_device for mutual exclusion; drivers using the async
 routines are responsible for their own synchronization and mutual
 exclusion.
 
@@ -347,11 +350,6 @@ exclusion.
 	attempts an autosuspend if the new value is <= 0 and the
 	device isn't suspended.
 
-	usb_autopm_set_interface() leaves pm_usage_count alone.
-	It attempts an autoresume if the value is > 0 and the device
-	is suspended, and it attempts an autosuspend if the value is
-	<= 0 and the device isn't suspended.
-
 	usb_autopm_get_interface_async() and
 	usb_autopm_put_interface_async() do almost the same things as
 	their non-async counterparts.  The differences are: they do
@@ -360,13 +358,11 @@ exclusion.
 	such as an URB's completion handler, but when they return the
 	device will not generally not yet be in the desired state.
 
-There also are a couple of utility routines drivers can use:
-
-	usb_autopm_enable() sets pm_usage_cnt to 0 and then calls
-	usb_autopm_set_interface(), which will attempt an autosuspend.
-
-	usb_autopm_disable() sets pm_usage_cnt to 1 and then calls
-	usb_autopm_set_interface(), which will attempt an autoresume.
+	usb_autopm_get_interface_no_resume() and
+	usb_autopm_put_interface_no_suspend() merely increment or
+	decrement the pm_usage_count value; they do not attempt to
+	carry out an autoresume or an autosuspend.  Hence they can be
+	called in an atomic context.
 
 The conventional usage pattern is that a driver calls
 usb_autopm_get_interface() in its open routine and
@@ -400,11 +396,11 @@ though, setting this flag won't cause the kernel to autoresume it.
 Normally a driver would set this flag in its probe method, at which
 time the device is guaranteed not to be autosuspended.)
 
-The usb_autopm_* routines have to run in a sleepable process context;
-they must not be called from an interrupt handler or while holding a
-spinlock.  In fact, the entire autosuspend mechanism is not well geared
-toward interrupt-driven operation.  However there is one thing a
-driver can do in an interrupt handler:
+The synchronous usb_autopm_* routines have to run in a sleepable
+process context; they must not be called from an interrupt handler or
+while holding a spinlock.  In fact, the entire autosuspend mechanism
+is not well geared toward interrupt-driven operation.  However there
+is one thing a driver can do in an interrupt handler:
 
 	usb_mark_last_busy(struct usb_device *udev);
 

drivers/usb/core/driver.c

@@ -948,8 +948,6 @@ static int usb_resume_device(struct usb_device *udev, pm_message_t msg)
 
  done:
 	dev_vdbg(&udev->dev, "%s: status %d\n", __func__, status);
-	if (status == 0)
-		udev->autoresume_disabled = 0;
 	return status;
 }
 
@@ -1280,11 +1278,6 @@ static int usb_resume_both(struct usb_device *udev, pm_message_t msg)
 
 	/* Propagate the resume up the tree, if necessary */
 	if (udev->state == USB_STATE_SUSPENDED) {
-		if ((msg.event & PM_EVENT_AUTO) &&
-				udev->autoresume_disabled) {
-			status = -EPERM;
-			goto done;
-		}
 		if (parent) {
 			status = usb_autoresume_device(parent);
 			if (status == 0) {
@@ -1638,8 +1631,6 @@ int usb_autopm_get_interface_async(struct usb_interface *intf)
 
 	if (intf->condition == USB_INTERFACE_UNBOUND)
 		status = -ENODEV;
-	else if (udev->autoresume_disabled)
-		status = -EPERM;
 	else {
 		atomic_inc(&intf->pm_usage_cnt);
 		if (atomic_read(&intf->pm_usage_cnt) > 0 &&
@@ -1652,28 +1643,6 @@ int usb_autopm_get_interface_async(struct usb_interface *intf)
 }
 EXPORT_SYMBOL_GPL(usb_autopm_get_interface_async);
 
-/**
- * usb_autopm_set_interface - set a USB interface's autosuspend state
- * @intf: the usb_interface whose state should be set
- *
- * This routine sets the autosuspend state of @intf's device according
- * to @intf's usage counter, which the caller must have set previously.
- * If the counter is <= 0, the device is autosuspended (if it isn't
- * already suspended and if nothing else prevents the autosuspend).  If
- * the counter is > 0, the device is autoresumed (if it isn't already
- * awake).
- */
-int usb_autopm_set_interface(struct usb_interface *intf)
-{
-	int	status;
-
-	status = usb_autopm_do_interface(intf, 0);
-	dev_vdbg(&intf->dev, "%s: status %d cnt %d\n",
-			__func__, status, atomic_read(&intf->pm_usage_cnt));
-	return status;
-}
-EXPORT_SYMBOL_GPL(usb_autopm_set_interface);
-
 #else
 
 void usb_autosuspend_work(struct work_struct *work)

drivers/usb/core/hub.c

@@ -71,6 +71,7 @@ struct usb_hub {
 
 	unsigned		mA_per_port;	/* current for each child */
 
+	unsigned		init_done:1;
 	unsigned		limited_power:1;
 	unsigned		quiescing:1;
 	unsigned		disconnected:1;
@@ -375,12 +376,13 @@ static void kick_khubd(struct usb_hub *hub)
 {
 	unsigned long	flags;
 
-	/* Suppress autosuspend until khubd runs */
-	atomic_set(&to_usb_interface(hub->intfdev)->pm_usage_cnt, 1);
-
 	spin_lock_irqsave(&hub_event_lock, flags);
 	if (!hub->disconnected && list_empty(&hub->event_list)) {
 		list_add_tail(&hub->event_list, &hub_event_list);
+
+		/* Suppress autosuspend until khubd runs */
+		usb_autopm_get_interface_no_resume(
+				to_usb_interface(hub->intfdev));
 		wake_up(&khubd_wait);
 	}
 	spin_unlock_irqrestore(&hub_event_lock, flags);
@@ -665,7 +667,7 @@ int usb_remove_device(struct usb_device *udev)
 }
 
 enum hub_activation_type {
-	HUB_INIT, HUB_INIT2, HUB_INIT3,
+	HUB_INIT, HUB_INIT2, HUB_INIT3,		/* INITs must come first */
 	HUB_POST_RESET, HUB_RESUME, HUB_RESET_RESUME,
 };
 
@@ -710,8 +712,8 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type)
 					msecs_to_jiffies(delay));
 
 			/* Suppress autosuspend until init is done */
-			atomic_set(&to_usb_interface(hub->intfdev)->
-					pm_usage_cnt, 1);
+			usb_autopm_get_interface_no_resume(
+					to_usb_interface(hub->intfdev));
 			return;		/* Continues at init2: below */
 		} else {
 			hub_power_on(hub, true);
@@ -818,6 +820,7 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type)
 	}
  init3:
 	hub->quiescing = 0;
+	hub->init_done = 1;
 
 	status = usb_submit_urb(hub->urb, GFP_NOIO);
 	if (status < 0)
@@ -827,6 +830,10 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type)
 
 	/* Scan all ports that need attention */
 	kick_khubd(hub);
+
+	/* Allow autosuspend if it was suppressed */
+	if (type <= HUB_INIT3)
+		usb_autopm_put_interface_async(to_usb_interface(hub->intfdev));
 }
 
 /* Implement the continuations for the delays above */
@@ -854,6 +861,11 @@ static void hub_quiesce(struct usb_hub *hub, enum hub_quiescing_type type)
 	int i;
 
 	cancel_delayed_work_sync(&hub->init_work);
+	if (!hub->init_done) {
+		hub->init_done = 1;
+		usb_autopm_put_interface_no_suspend(
+				to_usb_interface(hub->intfdev));
+	}
 
 	/* khubd and related activity won't re-trigger */
 	hub->quiescing = 1;
@@ -1176,7 +1188,10 @@ static void hub_disconnect(struct usb_interface *intf)
 
 	/* Take the hub off the event list and don't let it be added again */
 	spin_lock_irq(&hub_event_lock);
-	list_del_init(&hub->event_list);
+	if (!list_empty(&hub->event_list)) {
+		list_del_init(&hub->event_list);
+		usb_autopm_put_interface_no_suspend(intf);
+	}
 	hub->disconnected = 1;
 	spin_unlock_irq(&hub_event_lock);
 
@@ -3235,7 +3250,7 @@ static void hub_events(void)
 		 * disconnected while waiting for the lock to succeed. */
 		usb_lock_device(hdev);
 		if (unlikely(hub->disconnected))
-			goto loop;
+			goto loop2;
 
 		/* If the hub has died, clean up after it */
 		if (hdev->state == USB_STATE_NOTATTACHED) {
@@ -3384,11 +3399,15 @@ static void hub_events(void)
 			}
 		}
 
-loop_autopm:
-		/* Allow autosuspend if we're not going to run again */
-		if (list_empty(&hub->event_list))
-			usb_autopm_enable(intf);
-loop:
+ loop_autopm:
+		/* Balance the usb_autopm_get_interface() above */
+		usb_autopm_put_interface_no_suspend(intf);
+ loop:
+		/* Balance the usb_autopm_get_interface_no_resume() in
+		 * kick_khubd() and allow autosuspend.
+		 */
+		usb_autopm_put_interface(intf);
+ loop2:
 		usb_unlock_device(hdev);
 		kref_put(&hub->kref, hub_release);
 

drivers/usb/core/sysfs.c

@@ -327,21 +327,15 @@ static DEVICE_ATTR(autosuspend, S_IRUGO | S_IWUSR,
 
 static const char on_string[] = "on";
 static const char auto_string[] = "auto";
-static const char suspend_string[] = "suspend";
 
 static ssize_t
 show_level(struct device *dev, struct device_attribute *attr, char *buf)
 {
 	struct usb_device *udev = to_usb_device(dev);
 	const char *p = auto_string;
 
-	if (udev->state == USB_STATE_SUSPENDED) {
-		if (udev->autoresume_disabled)
-			p = suspend_string;
-	} else {
-		if (udev->autosuspend_disabled)
-			p = on_string;
-	}
+	if (udev->state != USB_STATE_SUSPENDED && udev->autosuspend_disabled)
+		p = on_string;
 	return sprintf(buf, "%s\n", p);
 }
 
@@ -353,44 +347,33 @@ set_level(struct device *dev, struct device_attribute *attr,
 	int len = count;
 	char *cp;
 	int rc = 0;
-	int old_autosuspend_disabled, old_autoresume_disabled;
+	int old_autosuspend_disabled;
 
 	cp = memchr(buf, '\n', count);
 	if (cp)
 		len = cp - buf;
 
 	usb_lock_device(udev);
 	old_autosuspend_disabled = udev->autosuspend_disabled;
-	old_autoresume_disabled = udev->autoresume_disabled;
 
 	/* Setting the flags without calling usb_pm_lock is a subject to
 	 * races, but who cares...
 	 */
 	if (len == sizeof on_string - 1 &&
 			strncmp(buf, on_string, len) == 0) {
 		udev->autosuspend_disabled = 1;
-		udev->autoresume_disabled = 0;
 		rc = usb_external_resume_device(udev, PMSG_USER_RESUME);
 
 	} else if (len == sizeof auto_string - 1 &&
 			strncmp(buf, auto_string, len) == 0) {
 		udev->autosuspend_disabled = 0;
-		udev->autoresume_disabled = 0;
 		rc = usb_external_resume_device(udev, PMSG_USER_RESUME);
 
-	} else if (len == sizeof suspend_string - 1 &&
-			strncmp(buf, suspend_string, len) == 0) {
-		udev->autosuspend_disabled = 0;
-		udev->autoresume_disabled = 1;
-		rc = usb_external_suspend_device(udev, PMSG_USER_SUSPEND);
-
 	} else
 		rc = -EINVAL;
 
-	if (rc) {
+	if (rc)
 		udev->autosuspend_disabled = old_autosuspend_disabled;
-		udev->autoresume_disabled = old_autoresume_disabled;
-	}
 	usb_unlock_device(udev);
 	return (rc < 0 ? rc : count);
 }