Re: usb dma patch

On Tue, Jul 08, 2003 at 03:45:24PM -0700, John-Mark Gurney wrote:
> Hello,
> 
> I have made usb bus_dma aware.  I have only tested this patch so far on
> an ohci controller in sparc64.  I do have problems with isochronous
> transfers, but I don't have an i386 box to test the original code on to
> make sure it isn't my changes.  Currently both umass and ums have been
> tested and are working on sparc64.  I would like to receive feed back
> on i386 to make sure things don't break there.

ohci code doesn't support isochronous so far.
There is a patch to add this kern/52589.

> The patch is at:
> http://people.FreeBSD.org/~jmg/usb_dma.diff

There are more changes than just bus_dma in this patchset.
E.g. changing commets for specs and adding verdors.

I've seen a number of changes in code places that are very similar to
ehci, but there are no such changes in ehci.

This was just with a quick look into the patchset so there might be
other issues as well.

You might also ask Josef Karthauser and Scott Long about this, because
they already spend some time into busdma'ing USB and they found some
performance issues with the current bus_dma implementation on FreeBSD.
You should contact Scott Long about details.

-- 
B.Walter                   BWCT                http://www.bwct.de
ticso_at_bwct.de                                  info_at_bwct.de