Hmm.. What would happen if I try to send a URB with 0 data size ?
thanks
Vladimir Dergachev
On Mon, 18 Feb 2002, David Brownell wrote:
> Right now the only portable solution is rather awkward.
> That is:
>
> (a) make sure urb->interval is long enough that it's
> probably not going to suffer interrupt/scheduling
> latency problems (causing extra transfers), and
> submit the URB
> (b) have your completion handler signal the thread
> doing initialization, say using"struct completion"
> and calling complete() on it;
> (c) have that initialization thread wait for that, using
> wait_for_completion() perhaps;
> (d) when that thead wakes up after one transfer,
> may a synchronous usb_unlink_urb() call.
> (e) you'll get one more completion call, with a
> special call saying it's unlinked.
> (f) now it's unlinked.
>
> (Normally the unlink would be done in disconnect
> processing, not device open... which has its own
> set of portability issues, being fixed in 2.5.)
>
> Less portable solutions involve making an async
> usb_unlink_urb() call in the completion handler,
> which works now for EHCI and OHCI (bugfix for
> UHCI will be forthcoming, says Johannes).
>
> Or the UHCI drivers support a "one shot" mode,
> with urb->interval of zero having special meaning.
>
> - Dave
>
>
>
> ----- Original Message -----
> From: "Vladimir Dergachev" <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Monday, February 18, 2002 10:44 AM
> Subject: [linux-usb-devel] stopping interrupt transfers..
>
>
> >
> > Stupid question:
> >
> > I have a device that has two interrupt endpoints - in and out.
> > During initialization I need to transfer two small packets to the devices.
> > The problem is that USB seems to keep transferring the last packet..
> > How do I stop this ? (usb_unlink_urb does not seem to help).
> >
> > thanks !
> >
> > Vladimir Dergachev
> >
>
>
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