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: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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@ -1050,8 +1050,15 @@ static int usb_suspend_both(struct usb_device *udev, pm_message_t msg)
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break;
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}
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}
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if (status == 0)
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if (status == 0) {
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/* Non-root devices don't need to do anything for FREEZE
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* or PRETHAW. */
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if (udev->parent && (msg.event == PM_EVENT_FREEZE ||
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msg.event == PM_EVENT_PRETHAW))
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goto done;
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status = usb_suspend_device(udev, msg);
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}
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/* If the suspend failed, resume interfaces that did get suspended */
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if (status != 0) {
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@ -193,10 +193,6 @@ static void generic_disconnect(struct usb_device *udev)
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static int generic_suspend(struct usb_device *udev, pm_message_t msg)
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{
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/* USB devices enter SUSPEND state through their hubs, but can be
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* marked for FREEZE as soon as their children are already idled.
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* But those semantics are useless, so we equate the two (sigh).
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*/
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return usb_port_suspend(udev);
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}
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