On Wed, 24 Oct 2012, Felipe Balbi wrote:
> > We see that after making the below change in "ohci_irq", the device
> > gets detected.
> > ---------------------------------------------------------------------------------------------------
> > --- a/drivers/usb/host/ohci-hcd.c
> > +++ b/drivers/usb/host/ohci-hcd.c
> > @@ -819,7 +819,7 @@ static irqreturn_t ohci_irq (struct usb_hcd *hcd)
> > * to turn on RHSC along with RD. But for remote wakeup events
> > * this might not happen.
> > */
> > - else if (ints & OHCI_INTR_RD) {
> > + if (ints & OHCI_INTR_RD) {
> > ---------------------------------------------------------------------------------------------------
> > Even in the OHCI specification (Sec 5.3 page 80), it is recommended to
> > check individual bits
> > (RHSC and RD).
> >
> > Can you please let us know if this change is valid and will not cause
> > any regression?
>
> This change makes sense to me. Unless we are dead sure those IRQ bits
> are mutually exclusive.
They are not mutually exclusive. That's the problem. Basically it
comes down to this:
if (OHCI_INTR_RHSC is set) {
do A;
do B;
} else if (OHCI_INTR_RD is set)
do B;
Since the bits aren't mutually exclusive, you can see that without the
"else" we would end up doing B twice.
Alan Stern
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