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/include/linux/usb.h b/include/linux/usb.h
index 5634a2d..0cd73ed 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -362,6 +362,7 @@
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 */