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 <[EMAIL PROTECTED]>
---
Index: usb-2.6/drivers/usb/core/generic.c
===================================================================
--- usb-2.6.orig/drivers/usb/core/generic.c
+++ usb-2.6/drivers/usb/core/generic.c
@@ -193,10 +193,6 @@ static void generic_disconnect(struct us
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);
}
Index: usb-2.6/drivers/usb/core/driver.c
===================================================================
--- usb-2.6.orig/drivers/usb/core/driver.c
+++ usb-2.6/drivers/usb/core/driver.c
@@ -1043,8 +1043,15 @@ static int usb_suspend_both(struct usb_d
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) {
-------------------------------------------------------------------------
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