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SubjectRe: [patch 19/26] USB: mutual exclusion for EHCI init and port resets
Still needs the following update, IMO ... 

====== CUT HERE
A recent patch added software synchronization during EHCI startup,
so ports aren't switched away from the companion controllers after
resets have started. This patch adds a short delay letting hardware
get a chance to finish that port switching before any new resets begin.

That is, both sides of that hardware race window need to be closed.

Signed-off-by: David Brownell <>
drivers/usb/host/ehci-hcd.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

--- g26.orig/drivers/usb/host/ehci-hcd.c 2007-11-13 16:07:12.000000000 -0800
+++ g26/drivers/usb/host/ehci-hcd.c 2007-11-13 16:13:01.000000000 -0800
@@ -594,12 +594,15 @@ static int ehci_run (struct usb_hcd *hcd
* from the companions to the EHCI controller. If any of the
* companions are in the middle of a port reset at the time, it
* could cause trouble. Write-locking ehci_cf_port_reset_rwsem
- * guarantees that no resets are in progress.
+ * guarantees that no resets are in progress. After we set CF,
+ * a short delay lets the hardware catch up; new resets shouldn't
+ * start before the port switching actions complete.
hcd->state = HC_STATE_RUNNING;
ehci_writel(ehci, FLAG_CF, &ehci->regs->configured_flag);
ehci_readl(ehci, &ehci->regs->command); /* unblock posted writes */
+ msleep(5);

temp = HC_VERSION(ehci_readl(ehci, &ehci->caps->hc_capbase));
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