Am Freitag, 29. Juni 2007 schrieb David Brownell:
> On Friday 29 June 2007, Oliver Neukum wrote:
> > Hi,
> >
> > I am trying to calculate worst cases memory requirements of EHCI.
> > For bulk transfers it seems to me that you need size/16384 (rounded up)
> > qtd and one qh. Is it really that easy?
>
> ISTR, yes. And interrupt transfers are the same.
>
> > What about the other transfer types?
>
> Control transfers are like bulk/intr, plus one more qtd.
>
> ISO is ISTR urb->number_of_packets plus a dummy qh.
> What do you count?
I am working on shifting all memory allocations to usb_alloc_urb().
Up to now I haven't required users of the API to specify the buffers
at usb_alloc_urb() time, just a maximum length. Therefore I need
the worst case.
Regards
Oliver
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