[patch 11/60] USB: fix up EHCI startup synchronization

[Greg KH]

2.6.23-stable review patch.  If anyone has any objections, please let us
know.

------------------
From: David Brownell <david-b@xxxxxxxxxxx>

patch 1cb52658b4f5b10a9e91f8e1c21ca2bcc1b9a3ca in mainline.

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
finish that port switching before any new resets begin ... so both
ends of that hardware race window are closed.

Signed-off-by: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx>
Cc: Dave Miller <davem@xxxxxxxxxxxxx>
Cc: Dely Sy <dely.l.sy@xxxxxxxxx>
Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 drivers/usb/host/ehci-hcd.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -575,12 +575,15 @@ 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
+	 * be started before the port switching actions could complete.
 	 */
 	down_write(&ehci_cf_port_reset_rwsem);
 	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);
 	up_write(&ehci_cf_port_reset_rwsem);
 
 	temp = HC_VERSION(ehci_readl(ehci, &ehci->caps->hc_capbase));

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