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USB: Implement PM FREEZE and PRETHAW

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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: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Alan Stern 2007-05-04 11:51:25 -04:00 committed by Greg Kroah-Hartman
parent 784a6e1cc4
commit 4d461095ef
2 changed files with 8 additions and 5 deletions
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9
drivers/usb/core/driver.c
View File

@ -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) {

4
drivers/usb/core/generic.c
View File

@ -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);
}