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Commit 4d461095 authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman
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USB: Implement PM FREEZE and PRETHAW 



This patch (as884) finally implements the time-saving semantics
possible with the Power Management FREEZE and PRETHAW events.  Their
proper handling requires only that devices be quiesced, with
interrupts and DMA turned off; non-root USB devices don't actually
need to be put in a suspended state.  The patch checks and avoids
doing the suspend call when possible.

Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 784a6e1c

drivers/usb/core/driver.c

+8 −1
Original line number Diff line number Diff line
@@ -1050,8 +1050,15 @@ static int usb_suspend_both(struct usb_device *udev, pm_message_t msg) 
				break;

		}

	}

	if (status == 0)

	if (status == 0) {



		/* Non-root devices don't need to do anything for FREEZE

		 * or PRETHAW. */

		if (udev->parent && (msg.event == PM_EVENT_FREEZE ||

				msg.event == PM_EVENT_PRETHAW))

			goto done;

		status = usb_suspend_device(udev, msg);

	}



	/* If the suspend failed, resume interfaces that did get suspended */

	if (status != 0) {

drivers/usb/core/generic.c

+0 −4
Original line number Diff line number Diff line
@@ -193,10 +193,6 @@ static void generic_disconnect(struct usb_device *udev) 


static int generic_suspend(struct usb_device *udev, pm_message_t msg)

{

	/* USB devices enter SUSPEND state through their hubs, but can be

	 * marked for FREEZE as soon as their children are already idled.

	 * But those semantics are useless, so we equate the two (sigh).

	 */

	return usb_port_suspend(udev);

}