RE: Scatter-gather list constraints

From: Alan Stern
Date: Wed Jun 25 2008 - 10:25:07 EST


On Tue, 24 Jun 2008, Perez-Gonzalez, Inaky wrote:

> >From: David Vrabel [mailto:david.vrabel@xxxxxxx]
> >
> >> That would be ideal. However there is no way to pass an S-G list
> along
> >> with an URB; there's no field for it in the data structure. And none
> >> of the existing host controller drivers support such a thing.
> >>
> >> I suppose we could add a field to struct urb and add a flag
> indicating
> >> whether the controller driver supports S-G lists.
> >
> >This is what I was thinking.
>
> That would simplify a *LOT* of WUSB wire-adapter code which now is a
> horrible kludge.

In what way would it simplify the code?

Note that usbcore already contains a scatter-gather library.
(Unfortunately the library is limited in usefulness because it needs to
run in process context.)

Alan Stern

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