On Mon, 19 Nov 2007, David Brownell wrote: > 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 <[EMAIL PROTECTED]> > --- > 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));
This addition certainly won't hurt. Did we ever get any feedback as to whether it actually helped? Alan Stern - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
