PROBLEM: USB isochronous urb leak on EHCI driver

Michael Tessier michael.tessier at
Wed Jan 7 04:38:29 AEDT 2015

> > > > That is interresting, however, I have an older kernel running an 
> > > > OHCI driver which is able to handle 4 codecs. Same usb hardware 
> > > > (codecs and hub), but older kernel on a different CPU, with much 
> > > > less power. This makes me believe that there's a solution to make it work...
> > > 
> > > Of course there is: Install an OHCI host controller and use it to drive your codecs.  It should work fine.

What do you mean by that? The host controller is embedded in the i.MX CPU...
Changing the CPU is not really an option to me. Unless I am missing

> > > 
> > > The periodic scheduling algorithm for OHCI is very different from the algorithm for EHCI.
> > 
> > According to your knowledge, how much time would you think it takes to 
> > change the EHCI driver with an OHCI one?
> I don't understand the question.
> >  And can you tell if the OHCI driver
> > will work on my hardware given that the Host controller of the i.MX512 
> > is a USB2.0 host controller? (OHCI was implemented for USB 1.x from 
> > what I
> > understand)
> The OHCI driver works with OHCI hardware and the EHCI driver works with EHCI hardware.  OHCI is USB-1.1 and EHCI is USB-2.  They are not interchangeable.

That was what I thought first...

> > I tried to do so several days ago with the built-in configurator (I am 
> > using "ltib"), but the configurator does not allow selecting the OHCI 
> > driver; I tried manually but it turned into compiler errors...
> It looks like the configurator is smart; it won't let you select the wrong driver for your hardware.
> Alan Stern

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