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USB: keep count of unsuspended children

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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: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Alan Stern 2006-11-22 16:55:54 -05:00 committed by Greg Kroah-Hartman
parent d25450c687
commit ee49fb5dc8
3 changed files with 38 additions and 11 deletions
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34
drivers/usb/core/driver.c
View File

@ -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)
status = usb_resume_device(udev);
if (parent)
usb_pm_unlock(parent);
else
status = usb_resume_device(udev);
}
} 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];

14
drivers/usb/core/hub.c
View File

@ -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;

1
include/linux/usb.h
View File

@ -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 */