Which kernel?
Ubuntu Linux 2.6.35-25-generic
I've tried various kernels from 2.6.32 to 2.6.35 various Ubuntu and Debian kernels. All experience the same. I have not yet compiled a kernel myself since it's a lot of work and the performance gains are negligible. Since the problem persists in all kernels I've tried it makes me suspect that the bug is in the master tree not something that was added on in a distro kernel.
Shooting from the hip (and also digging in 2.6.26.5 sources)... looks
like there was a timeout when calling usb_set_interface()
(drivers/usb/core/message.c). The urb transfers look like they
stalled rather than failed to allocate bandwidth. That makes me think
there's a bad cable, bad USB controller, bad USB controller /driver/,
bad format request, bad device, or something like that.
That sounds consistent with my reports. It's speculation, but at least we have that...
I bought two PCI USB cards to test against. One is PCI Express USB 3.0 the other is PCI USB 2.0 - I'll report the results.
Assuming that the on-board hardware is being unusually slow - this ought to fix it. If it's deeper in the core hardware I should probably scrap this board and get something that works properly. Either way I ought to know something soon. :-D
I'll add the USB cards tonight. Stay tuned! :-D
...Rods ;-)