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, 7 insertions, 16 deletions

diff --git a/drivers/usb/core/sysfs.c b/drivers/usb/core/sysfs.c
index 5a1a0e2..313e241 100644
--- a/drivers/usb/core/sysfs.c
+++ b/drivers/usb/core/sysfs.c
@@ -389,34 +389,25 @@ set_level(struct device *dev, struct device_attribute *attr,
 	struct usb_device *udev = to_usb_device(dev);
 	int len = count;
 	char *cp;
-	int rc = 0;
-	int old_autosuspend_disabled;
+	int rc;
 
 	cp = memchr(buf, '\n', count);
 	if (cp)
 		len = cp - buf;
 
 	usb_lock_device(udev);
-	old_autosuspend_disabled = udev->autosuspend_disabled;
 
-	/* Setting the flags without calling usb_pm_lock is a subject to
-	 * races, but who cares...
-	 */
 	if (len == sizeof on_string - 1 &&
-			strncmp(buf, on_string, len) == 0) {
-		udev->autosuspend_disabled = 1;
-		rc = usb_external_resume_device(udev, PMSG_USER_RESUME);
+			strncmp(buf, on_string, len) == 0)
+		rc = usb_disable_autosuspend(udev);
 
-	} else if (len == sizeof auto_string - 1 &&
-			strncmp(buf, auto_string, len) == 0) {
-		udev->autosuspend_disabled = 0;
-		rc = usb_external_resume_device(udev, PMSG_USER_RESUME);
+	else if (len == sizeof auto_string - 1 &&
+			strncmp(buf, auto_string, len) == 0)
+		rc = usb_enable_autosuspend(udev);
 
-	} else
+	else
 		rc = -EINVAL;
 
-	if (rc)
-		udev->autosuspend_disabled = old_autosuspend_disabled;
 	usb_unlock_device(udev);
 	return (rc < 0 ? rc : count);
 }