Commit ee49fb5d authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman
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USB: keep count of unsuspended children 



This patch (as818b) simplifies autosuspend processing by keeping track
of the number of unsuspended children of each USB hub.  This will
permit us to avoid a good deal of unnecessary work all the time; we
will no longer have to create a bunch of workqueue entries to carry
out autosuspend requests, only to have them fail because one of the
hub's children isn't suspended.

The basic idea is simple.  There already is a usage counter in the
usb_device structure for preventing autosuspends.  The patch just
increments that counter for every unsuspended child.  There's only one
tricky part: When a device disconnects we need to remember whether it
was suspended at the time (leave the counter alone) or not (decrement
the counter).

Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent d25450c6

drivers/usb/core/driver.c

+23 −11
Original line number Diff line number Diff line
@@ -1048,7 +1048,7 @@ int usb_suspend_both(struct usb_device *udev, pm_message_t msg) 


	/* If the suspend succeeded, propagate it up the tree */

	} else if (parent)

		usb_autosuspend_device(parent, 0);

		usb_autosuspend_device(parent, 1);



	// dev_dbg(&udev->dev, "%s: status %d\n", __FUNCTION__, status);

	return status;
@@ -1096,9 +1096,25 @@ int usb_resume_both(struct usb_device *udev) 
	/* Propagate the resume up the tree, if necessary */

	if (udev->state == USB_STATE_SUSPENDED) {

		if (parent) {

			usb_pm_lock(parent);

			parent->auto_pm = 1;

			status = usb_resume_both(parent);

			status = usb_autoresume_device(parent, 1);

			if (status == 0) {

				status = usb_resume_device(udev);

				if (status) {

					usb_autosuspend_device(parent, 1);



					/* It's possible usb_resume_device()

					 * failed after the port was

					 * unsuspended, causing udev to be

					 * logically disconnected.  We don't

					 * want usb_disconnect() to autosuspend

					 * the parent again, so tell it that

					 * udev disconnected while still

					 * suspended. */

					if (udev->state ==

							USB_STATE_NOTATTACHED)

						udev->discon_suspended = 1;

				}

			}

		} else {



			/* We can't progagate beyond the USB subsystem,
@@ -1107,11 +1123,9 @@ int usb_resume_both(struct usb_device *udev) 
			if (udev->dev.parent->power.power_state.event !=

					PM_EVENT_ON)

				status = -EHOSTUNREACH;

		}

		if (status == 0)

			else

				status = usb_resume_device(udev);

		if (parent)

			usb_pm_unlock(parent);

 		}

	} else {



		/* Needed only for setting udev->dev.power.power_state.event
@@ -1119,8 +1133,6 @@ int usb_resume_both(struct usb_device *udev) 
		status = usb_resume_device(udev);

	}



	/* Now the parent won't suspend until we are finished */



	if (status == 0 && udev->actconfig) {

		for (i = 0; i < udev->actconfig->desc.bNumInterfaces; i++) {

			intf = udev->actconfig->interface[i];

drivers/usb/core/hub.c

+14 −0
Original line number Diff line number Diff line
@@ -1039,6 +1039,8 @@ static void recursively_mark_NOTATTACHED(struct usb_device *udev) 
		if (udev->children[i])

			recursively_mark_NOTATTACHED(udev->children[i]);

	}

	if (udev->state == USB_STATE_SUSPENDED)

		udev->discon_suspended = 1;

	udev->state = USB_STATE_NOTATTACHED;

}
@@ -1228,6 +1230,14 @@ void usb_disconnect(struct usb_device **pdev) 
	*pdev = NULL;

	spin_unlock_irq(&device_state_lock);



	/* Decrement the parent's count of unsuspended children */

	if (udev->parent) {

		usb_pm_lock(udev);

		if (!udev->discon_suspended)

			usb_autosuspend_device(udev->parent, 1);

		usb_pm_unlock(udev);

	}



	put_device(&udev->dev);

}
@@ -1356,6 +1366,10 @@ static int __usb_new_device(void *void_data) 
		goto fail;

	}



	/* Increment the parent's count of unsuspended children */

	if (udev->parent)

		usb_autoresume_device(udev->parent, 1);



exit:

	module_put(THIS_MODULE);

	return err;

include/linux/usb.h

+1 −0
Original line number Diff line number Diff line
@@ -362,6 +362,7 @@ struct usb_device { 
	u8 portnum;			/* Parent port number (origin 1) */

	u8 level;			/* Number of USB hub ancestors */



	unsigned discon_suspended:1;	/* Disconnected while suspended */

	unsigned have_langid:1;		/* whether string_langid is valid */

	int string_langid;		/* language ID for strings */

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