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>
diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index 2b39583..057eeab 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -1415,6 +1415,48 @@
#ifdef CONFIG_USB_SUSPEND
+/**
+ * usb_enable_autosuspend - allow a USB device to be autosuspended
+ * @udev: the USB device which may be autosuspended
+ *
+ * This routine allows @udev to be autosuspended. An autosuspend won't
+ * take place until the autosuspend_delay has elapsed and all the other
+ * necessary conditions are satisfied.
+ *
+ * The caller must hold @udev's device lock.
+ */
+int usb_enable_autosuspend(struct usb_device *udev)
+{
+ if (udev->autosuspend_disabled) {
+ udev->autosuspend_disabled = 0;
+ usb_autosuspend_device(udev);
+ }
+ return 0;
+}
+EXPORT_SYMBOL_GPL(usb_enable_autosuspend);
+
+/**
+ * usb_disable_autosuspend - prevent a USB device from being autosuspended
+ * @udev: the USB device which may not be autosuspended
+ *
+ * This routine prevents @udev from being autosuspended and wakes it up
+ * if it is already autosuspended.
+ *
+ * The caller must hold @udev's device lock.
+ */
+int usb_disable_autosuspend(struct usb_device *udev)
+{
+ int rc = 0;
+
+ if (!udev->autosuspend_disabled) {
+ rc = usb_autoresume_device(udev);
+ if (rc == 0)
+ udev->autosuspend_disabled = 1;
+ }
+ return rc;
+}
+EXPORT_SYMBOL_GPL(usb_disable_autosuspend);
+
/* Internal routine to adjust a device's usage counter and change
* its autosuspend state.
*/