Am Samstag, 7. Juli 2007 schrieb David Brownell:
> On Saturday 07 July 2007, Alan Stern wrote:
> > On Fri, 6 Jul 2007, David Brownell wrote:
> >
> > > > The total number of interrupts would depend on the HCD. Right now OHCI
> > > > is probably the worst case.
> > >
> > > Worst??? No, I'd say it's intermediate between UHCI (lots of IRQs)
> > > and EHCI (can have virtually none).
> >
> > Is ehci-hcd really capable of doing that?
>
> Yes; submit a big scatterlist of 128 KBytes, and unless there's
> some other controller operation going on at the same time there
> won't be an IRQ until the very last packet completes.
This is very good and worth preserving.
IMHO the storage driver should be optimized for EHCI. The others must
work, but the most important is EHCI. So this would point to dynamic
allocation of URBs with one preallocated URB to fall back to for the ENOMEM
case.
This brings me to an idea.
Is it possible to accept the next scsi request while the current request is
being executed? That way, when the first request finishes, the URBs
could be retained if they are needed right away and otherwise freed.
Regards
Oliver
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