USB: implement usb_enable_autosuspend

This patch (as1326) adds usb_enable_autosuspend() and
usb_disable_autosuspend() routines for use by drivers.  If a driver
knows that its device can handle suspends and resumes correctly, it
can enable autosuspend all by itself.  This is equivalent to the user
writing "auto" to the device's power/level attribute.

The implementation differs slightly from what it used to be.  Now
autosuspend is disabled simply by doing usb_autoresume_device() (to
increment the usage counter) and enabled by doing
usb_autosuspend_device() (to decrement the usage counter).

The set_level() attribute method is updated to use the new routines,
and the USB Power-Management documentation is updated.

The patch adds a usb_enable_autosuspend() call to the hub driver's
probe routine, allowing the special-case code for hubs in quirks.c to
be removed.

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

1 files changed, 8 insertions, 0 deletions

diff --git a/include/linux/usb.h b/include/linux/usb.h
index 332eaea61021..e6419ac89ea2 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -542,6 +542,9 @@ extern struct usb_device *usb_find_device(u16 vendor_id, u16 product_id);
 
 /* USB autosuspend and autoresume */
 #ifdef CONFIG_USB_SUSPEND
+extern int usb_enable_autosuspend(struct usb_device *udev);
+extern int usb_disable_autosuspend(struct usb_device *udev);
+
 extern int usb_autopm_get_interface(struct usb_interface *intf);
 extern void usb_autopm_put_interface(struct usb_interface *intf);
 extern int usb_autopm_get_interface_async(struct usb_interface *intf);
@@ -565,6 +568,11 @@ static inline void usb_mark_last_busy(struct usb_device *udev)
 
 #else
 
+static inline int usb_enable_autosuspend(struct usb_device *udev)
+{ return 0; }
+static inline int usb_disable_autosuspend(struct usb_device *udev)
+{ return 0; }
+
 static inline int usb_autopm_get_interface(struct usb_interface *intf)
 { return 0; }
 static inline int usb_autopm_get_interface_async(struct usb_interface *intf)