On Wed, 18 Jul 2007, Oliver Neukum wrote:
> Am Mittwoch 18 Juli 2007 schrieb Alan Stern:
> > On Wed, 18 Jul 2007, Oliver Neukum wrote:
> >
> > > > Am Mittwoch 18 Juli 2007 schrieb Alan Stern:
> > > > int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
> > > > {
> > > > - int pipe, temp, max;
> > > > - struct usb_device *dev;
> > > > - int is_out;
> > > > + int xfertype, max;
> > > > + struct usb_device *dev;
> > > > + struct usb_host_endpoint *ep;
> > > > + int is_out;
> > >
> > > This is a bit odd. Using a pointer the direction info should be included.
> >
> > I don't understand. Included where?
>
> struct usb_host_endpoint
The direction information is part of the endpoint descriptor stored in
the usb_host_endpoint. But control endpoints don't have direction bits
in their descriptors, since they are bidirectional.
> > > Or you could use endpoint numbers, which would remove some issues
> > > with enummeration.
> >
> > That's essentially the same as using a pipe, since some of the bits in
> > a pipe _are_ the endpoint number.
>
> Only some, but yes, it is much closer. Still if you give ep, dev and is_out
> should be implicit.
We currently don't have any way to go from the endpoint structure to
the usb_device structure, so dev is not implicit. And while is_out is
implicit for non-control endpoints, what's wrong with storing it in a
local variable for convenience? You may note that I didn't add the
is_out variable; it has been there for a long time.
> And how do you submit the first URBs? Are you going
> to fake a struct usb_host_endpoint for endpoint 0 ?
That's exactly what we do right now.
Alan Stern
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