On Tuesday 12 October 2004 2:03 pm, Alan Stern wrote:
> On Mon, 11 Oct 2004, David Brownell wrote:
>
> > > I'm worried that this patch will no longer be adequate when the
> > > initialization sequence changes. If I knew exactly what needed to be
> > > fixed, I'd be a lot more confident...
> >
> > I know the feeling, believe me! On the other hand, usbcore
> > should be scrubbing out that state anyway. It's not the kind of
> > API glitch that HCDs should need to notice, and scrubbing it
> > out will let me finally eliminate some ugly code from the
> > OHCI and EHCI drivers.
>
> There's already code in hub_port_init to scrub ep0 for full-speed devices
> when the ep0 maxpacket value is different from the initial guess. I can
> make that unconditional, for all devices. Would that be okay?
Not needed. There are two cases where an HCD needs records
to be invalidated (unless it's UHCI or other hardware that doesn't
"know" such things:
(a) HCD records endpoint address, which changes after SET_ADDRESS.
that's what this patch addressed.
(b) HCD records ep0maxpacket, which usbcore may have guessed
wrong for full speed devices.
Only an issue for ep0, only during enumeration, only those cases.
Separate "scrub that state" calls are appropriate.
- Dave
> I've been planning on doing something like this anyway. Some devices
> enumerate more reliably under UHCI without full-speed bandwidth
> reclamation. The easiest way to set that up is to put control messages
> for devices in the DEFAULT state on the low-speed control queue (which
> isn't subject to bandwidth reclamation). It then would become necessary
> to scrub the endpoint state so that later the messages could go on the
> full-speed control queue.
>
> Alan Stern
>
>
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