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USB: implement usb_enable_autosuspend

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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>
This commit is contained in:
Alan Stern
2010-01-08 12:56:54 -05:00
committed by Greg Kroah-Hartman
parent 0c4db6df91
commit 088f7fec8a
6 changed files with 82 additions and 21 deletions
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23
drivers/usb/core/sysfs.c
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@@ -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);
}