Messages in this thread Patch in this message | | | Date | Mon, 19 Nov 2007 10:41:28 -0800 | From | David Brownell <> | Subject | Re: [patch 19/26] USB: mutual exclusion for EHCI init and port resets |
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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 <dbrownell@users.sourceforge.net> --- 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. */ 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)); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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