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: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index 40c1bf0..0fa15bd 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -1048,7 +1048,7 @@
/* 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 @@
/* 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 @@
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 @@
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];