Commit 5899f1e0 authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman
Browse files

USB: change handling of negative autosuspend delays 



This patch (as1327) changes the way negative autosuspend delays
prevent device from autosuspending.  The current code checks for
negative values explicitly in the autosuspend_check() routine.  The
updated code keeps things from getting that far by using
usb_autoresume_device() to increment the usage counter when a negative
delay is set, and by using usb_autosuspend_device() to decrement the
usage counter when a non-negative delay is set.

This complicates the set_autosuspend() attribute method code slightly,
but it will reduce the overall power management overhead.

Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 088f7fec

drivers/usb/core/quirks.c

+10 −0
Original line number Diff line number Diff line
@@ -103,11 +103,21 @@ void usb_detect_quirks(struct usb_device *udev) 
		dev_dbg(&udev->dev, "USB quirks for this device: %x\n",

				udev->quirks);



#ifdef	CONFIG_USB_SUSPEND



	/* By default, disable autosuspend for all devices.  The hub driver

	 * will enable it for hubs.

	 */

	usb_disable_autosuspend(udev);



	/* Autosuspend can also be disabled if the initial autosuspend_delay

	 * is negative.

	 */

	if (udev->autosuspend_delay < 0)

		usb_autoresume_device(udev);



#endif



	/* For the present, all devices default to USB-PERSIST enabled */

#if 0		/* was: #ifdef CONFIG_PM */

	/* Hubs are automatically enabled for USB-PERSIST */

drivers/usb/core/sysfs.c

+17 −5
Original line number Diff line number Diff line
@@ -346,7 +346,8 @@ set_autosuspend(struct device *dev, struct device_attribute *attr, 
		const char *buf, size_t count)

{

	struct usb_device *udev = to_usb_device(dev);

	int value;

	int value, old_delay;

	int rc;



	if (sscanf(buf, "%d", &value) != 1 || value >= INT_MAX/HZ ||

			value <= - INT_MAX/HZ)
@@ -354,13 +355,24 @@ set_autosuspend(struct device *dev, struct device_attribute *attr, 
	value *= HZ;



	usb_lock_device(udev);

	old_delay = udev->autosuspend_delay;

	udev->autosuspend_delay = value;



	if (old_delay < 0) {	/* Autosuspend wasn't allowed */

		if (value >= 0)

		usb_try_autosuspend_device(udev);

	else {

		if (usb_autoresume_device(udev) == 0)

			usb_autosuspend_device(udev);

	} else {		/* Autosuspend was allowed */

		if (value < 0) {

			rc = usb_autoresume_device(udev);

			if (rc < 0) {

				count = rc;

				udev->autosuspend_delay = old_delay;

			}

		} else {

			usb_try_autosuspend_device(udev);

		}

	}



	usb_unlock_device(udev);

	return count;

}

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