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.
> With the unmodified source, the execution doesn't stop at this point
> but at the next readl (I tried inserting printk and readl instructions
> after the writel which restores the fminterval and the execution
> stopped before exiting quirk_usb_handoff_ohci).
> I don't know how it relates to the ACPI message... (see bug 43073 in
> bugzilla.kernel.org).
I don't know just what the problem is either, but there's nothing wrong
with delaying startup by 1 us. In fact, all we have to do is reorder
the statements within the loop. Is this patch okay for you?
Alan Stern
Index: usb-3.4/drivers/usb/host/pci-quirks.c
===================================================================
--- usb-3.4.orig/drivers/usb/host/pci-quirks.c
+++ usb-3.4/drivers/usb/host/pci-quirks.c
@@ -520,9 +520,10 @@ static void __devinit quirk_usb_handoff_
/* reset requires max 10 us delay */
for (cnt = 30; cnt > 0; --cnt) { /* ... allow extra time */
+ /* Some controllers enable HCR too soon, so always delay 1 us */
+ udelay(1);
if ((readl(base + OHCI_CMDSTATUS) & OHCI_HCR) == 0)
break;
- udelay(1);
}
writel(fminterval, base + OHCI_FMINTERVAL);
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