Re: [linux-usb-devel] Re: USB EHCI Problem with Low Speed

Re: [linux-usb-devel] Re: USB EHCI Problem with Low Speed

[David Brownell]

> > http://marc.theaimsgroup.com/?l=linux-usb-devel&m=112439094723976&w=2

Yes please ... these issues do seem to be intermittent and hardware-specific,
so we'd like to know if relaxed enumeration timings work better for the folk
who have these problems.


> Yes, Dominik, please do. The TT was a poor guess, because IIRC 2.6.8
> did not have the support for TT, so it could not get it wrong.

Actually every EHCI version from kernel.org has always supported TTs;
I didn't submit it until full and low speed devices would enumerate,
an I could use USB keyboards and mice.  The reason it's a poor guess
is that TT support has nothing to do with this level of problem.  ;)

What's changed is how smart the _periodic scheduling_ support is.
The original algorithm took some major simplifying shortcuts, which
reduced functionality.  The latest code doesn't have very many of
those shortcuts.  It's accordingly a LOT more complicated.  Some
of the newer features need work yet (e.g. scheduling ISO OUT).

- Dave