[PATCH] EHCI: fix remote wakeup regression in 2.6.21-rc

There is one significant difference between the behavior of root hubs
(as embodied in host controller hardware) and external hubs: When a
remote-wakeup signal is received, an external hub sends an interrupt
message at the _end_ of the resume sequence but a root hub generates
and interrupt at the _beginning_ of the resume sequence.  The host
system must poll for the end of the sequence.

When ehci-hcd was converted to interrupt-driven operation instead of
using polling, the remaining need for this particular poll was
overlooked.  This patch (as894) fixes the problem.

Signed-off-by: Alan Stern <[email protected]>

---

Greg:

This needs to go into 2.6.21.  You can demonstrate the regression quite 
easily, as follows:  Plug in a high-speed device, like a USB flash drive, 
to prevent the root hub from suspending.  Then plug in an unpopulated 
high-speed hub.  Wait a couple of seconds for the hub to be suspended, 
then try plugging anything into the hub.  Without this patch, nothing will 
happen.

There still remains a 20-ms race between remote wakeup and suspend.  But 
fixing it will require more work; this patch is necessary in any case and 
it will be fine for 2.6.21.

Alan Stern


Index: usb-2.6/drivers/usb/host/ehci-hcd.c
===================================================================
--- usb-2.6.orig/drivers/usb/host/ehci-hcd.c
+++ usb-2.6/drivers/usb/host/ehci-hcd.c
@@ -671,6 +671,7 @@ static irqreturn_t ehci_irq (struct usb_
 			 */
 			ehci->reset_done [i] = jiffies + msecs_to_jiffies (20);
 			ehci_dbg (ehci, "port %d remote wakeup\n", i + 1);
+			mod_timer(&hcd->rh_timer, ehci->reset_done[i]);
 		}
 	}
 


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