On Thu, 26 Apr 2012, Greg KH wrote:
> On Thu, Apr 26, 2012 at 10:25:41AM -0400, Alan Stern wrote:
> > On Thu, 26 Apr 2012, Calin Demian wrote:
> >
> > > I don't know how, but adding the following line in function
> > > quirk_usb_handoff_ohci makes the system work fine:
> > >
> > > /* reset requires max 10 us delay */
> > > + udelay(1);
> > > for (cnt = 30; cnt > 0; --cnt) { /* ... allow extra time */
> > > if ((readl(base + OHCI_CMDSTATUS) & OHCI_HCR) == 0)
> > >
> > > I observed thad the condition in the for loop is allways true, so the
> > > delay inside the loop is never executed.
>
> That implies that something is wrong with the complier here, and it
> optimized out the loop? Are you sure that really happened?
Here's the complete context:
/* reset requires max 10 us delay */
for (cnt = 30; cnt > 0; --cnt) { /* ... allow extra time */
if ((readl(base + OHCI_CMDSTATUS) & OHCI_HCR) == 0)
break;
udelay(1);
}
I think Calim means that the "(readl(base + OHCI_CMDSTATUS) & OHCI_HCR)
== 0" test succeeds on the first pass through the loop, so we break out
early and the udelay(1) statement never gets executed.
Alan Stern
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