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>
diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index 38c3dd2..63d4794 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -1050,8 +1050,15 @@
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) {
diff --git a/drivers/usb/core/generic.c b/drivers/usb/core/generic.c
index 9bbcb20..e7ec9b6 100644
--- a/drivers/usb/core/generic.c
+++ b/drivers/usb/core/generic.c
@@ -193,10 +193,6 @@
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);
}
