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USB: change handling of negative autosuspend delays

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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@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Alan Stern
2010-01-08 12:57:02 -05:00
committed by Greg Kroah-Hartman
parent 088f7fec8a
commit 5899f1e020
2 changed files with 27 additions and 5 deletions
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10
drivers/usb/core/quirks.c
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@@ -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 */