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USB: fix up EHCI startup synchronization 

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@users.sourceforge.net>
Cc: Dave Miller <davem@davemloft.net>
Cc: Dely Sy <dely.l.sy@intel.com>
Cc: stable <stable@kernel.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
David Brownell 2007-11-13 16:22:30 -08:00 committed by Greg Kroah-Hartman
parent 5cf1973a44
commit 1cb52658b4
1 changed files with 4 additions and 1 deletions
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5
drivers/usb/host/ehci-hcd.c
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@ -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));