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: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
---
Index: usb-2.6/drivers/usb/core/sysfs.c
===================================================================
--- usb-2.6.orig/drivers/usb/core/sysfs.c
+++ usb-2.6/drivers/usb/core/sysfs.c
@@ -340,7 +340,8 @@ set_autosuspend(struct device *dev, stru
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)
@@ -348,13 +349,24 @@ set_autosuspend(struct device *dev, stru
value *= HZ;
usb_lock_device(udev);
+ old_delay = udev->autosuspend_delay;
udev->autosuspend_delay = value;
- if (value >= 0)
- usb_try_autosuspend_device(udev);
- else {
- if (usb_autoresume_device(udev) == 0)
+
+ if (old_delay < 0) { /* Autosuspend wasn't allowed */
+ if (value >= 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;
}
Index: usb-2.6/drivers/usb/core/quirks.c
===================================================================
--- usb-2.6.orig/drivers/usb/core/quirks.c
+++ usb-2.6/drivers/usb/core/quirks.c
@@ -103,11 +103,21 @@ void usb_detect_quirks(struct usb_device
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 */
--
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